diff --git a/pkg/bitmap/assets_test/circle_case_00.txt b/internal/bitmap/assets_test/circle_case_00.txt
similarity index 100%
rename from pkg/bitmap/assets_test/circle_case_00.txt
rename to internal/bitmap/assets_test/circle_case_00.txt
diff --git a/pkg/bitmap/assets_test/circle_case_01.txt b/internal/bitmap/assets_test/circle_case_01.txt
similarity index 100%
rename from pkg/bitmap/assets_test/circle_case_01.txt
rename to internal/bitmap/assets_test/circle_case_01.txt
diff --git a/pkg/bitmap/assets_test/circle_case_02.txt b/internal/bitmap/assets_test/circle_case_02.txt
similarity index 100%
rename from pkg/bitmap/assets_test/circle_case_02.txt
rename to internal/bitmap/assets_test/circle_case_02.txt
diff --git a/pkg/bitmap/assets_test/circle_case_03.txt b/internal/bitmap/assets_test/circle_case_03.txt
similarity index 100%
rename from pkg/bitmap/assets_test/circle_case_03.txt
rename to internal/bitmap/assets_test/circle_case_03.txt
diff --git a/pkg/bitmap/assets_test/circle_case_04.txt b/internal/bitmap/assets_test/circle_case_04.txt
similarity index 100%
rename from pkg/bitmap/assets_test/circle_case_04.txt
rename to internal/bitmap/assets_test/circle_case_04.txt
diff --git a/pkg/bitmap/bitmap.go b/internal/bitmap/bitmap.go
similarity index 100%
rename from pkg/bitmap/bitmap.go
rename to internal/bitmap/bitmap.go
diff --git a/pkg/bitmap/bitmap_test.go b/internal/bitmap/bitmap_test.go
similarity index 99%
rename from pkg/bitmap/bitmap_test.go
rename to internal/bitmap/bitmap_test.go
index d294ddc..22104bb 100644
--- a/pkg/bitmap/bitmap_test.go
+++ b/internal/bitmap/bitmap_test.go
@@ -7,7 +7,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/bitmap"
+	"github.com/iliadenisov/galaxy/internal/bitmap"
 )
 
 func TestBitVectorSize(t *testing.T) {
diff --git a/pkg/bitmap/export_test.go b/internal/bitmap/export_test.go
similarity index 100%
rename from pkg/bitmap/export_test.go
rename to internal/bitmap/export_test.go
diff --git a/internal/controller/controller.go b/internal/controller/controller.go
new file mode 100644
index 0000000..33a3ff8
--- /dev/null
+++ b/internal/controller/controller.go
@@ -0,0 +1,71 @@
+package controller
+
+import (
+	"fmt"
+
+	"github.com/iliadenisov/galaxy/internal/model/game"
+	"github.com/iliadenisov/galaxy/internal/repo"
+)
+
+type Repo interface {
+	// Lock must be called before any repository operations
+	Lock() error
+
+	// Release must be called after first and only repository operation
+	Release() error
+
+	// SaveTurn stores just generated new turn
+	SaveTurn(uint, game.Game) error
+
+	// SaveState stores current game state updated between turns
+	SaveState(game.Game) error
+
+	// LoadState retrieves game current state
+	LoadState() (game.Game, error)
+}
+
+type Ctrl struct {
+	param Param
+	Repo  Repo
+}
+
+type Param struct {
+	StoragePath string
+}
+
+func NewController(configure func(*Param)) (*Ctrl, error) {
+	c := &Param{
+		StoragePath: ".",
+	}
+	if configure != nil {
+		configure(c)
+	}
+	r, err := repo.NewFileRepo(c.StoragePath)
+	if err != nil {
+		return nil, err
+	}
+	return &Ctrl{
+		param: *c,
+		Repo:  r,
+	}, nil
+}
+
+func (c *Ctrl) ExecuteInit(consumer func(Repo)) error {
+	if err := c.Repo.Lock(); err != nil {
+		return fmt.Errorf("execute: lock failed: %s", err)
+	}
+	consumer(c.Repo)
+	return c.Repo.Release()
+}
+
+func (c *Ctrl) Execute(consumer func(Repo, game.Game)) error {
+	if err := c.Repo.Lock(); err != nil {
+		return fmt.Errorf("execute: lock failed: %s", err)
+	}
+	g, err := c.Repo.LoadState()
+	if err != nil {
+		return err
+	}
+	consumer(c.Repo, g)
+	return c.Repo.Release()
+}
diff --git a/pkg/game/generator.go b/internal/controller/generate.go
similarity index 95%
rename from pkg/game/generator.go
rename to internal/controller/generate.go
index bf37990..ddb42d7 100644
--- a/pkg/game/generator.go
+++ b/internal/controller/generate.go
@@ -1,4 +1,4 @@
-package game
+package controller
 
 import (
 	"fmt"
@@ -6,11 +6,11 @@ import (
 	"slices"
 
 	"github.com/google/uuid"
-	"github.com/iliadenisov/galaxy/pkg/generator"
-	"github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/generator"
+	"github.com/iliadenisov/galaxy/internal/model/game"
 )
 
-func newGame(r Repo, races []string) (uuid.UUID, error) {
+func NewGame(r Repo, races []string) (uuid.UUID, error) {
 	m, err := generator.Generate(func(ms *generator.MapSetting) {
 		ms.Players = uint32(len(races))
 	})
diff --git a/pkg/game/generator_test.go b/internal/controller/generate_test.go
similarity index 82%
rename from pkg/game/generator_test.go
rename to internal/controller/generate_test.go
index 176a11b..d8e2b9b 100644
--- a/pkg/game/generator_test.go
+++ b/internal/controller/generate_test.go
@@ -1,4 +1,4 @@
-package game
+package controller_test
 
 import (
 	"fmt"
@@ -6,9 +6,10 @@ import (
 	"testing"
 
 	"github.com/google/uuid"
-	"github.com/iliadenisov/galaxy/pkg/model/game"
-	"github.com/iliadenisov/galaxy/pkg/repo"
-	"github.com/iliadenisov/galaxy/pkg/util"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+	"github.com/iliadenisov/galaxy/internal/repo"
+	"github.com/iliadenisov/galaxy/internal/util"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -25,7 +26,7 @@ func TestNewGame(t *testing.T) {
 		races[i] = fmt.Sprintf("race_%02d", i)
 	}
 	assert.NoError(t, r.Lock())
-	gameID, err := newGame(r, races)
+	gameID, err := controller.NewGame(r, races)
 	assert.NoError(t, err)
 
 	assert.FileExists(t, filepath.Join(root, "state.json"))
diff --git a/pkg/error/generic.go b/internal/error/generic.go
similarity index 95%
rename from pkg/error/generic.go
rename to internal/error/generic.go
index 1c2761e..f3e16e4 100644
--- a/pkg/error/generic.go
+++ b/internal/error/generic.go
@@ -14,6 +14,7 @@ const (
 	ErrDeleteShipTypePlanetProduction = 5001
 	ErrDeleteSciencePlanetProduction  = 5002
 	ErrMergeShipTypeNotEqual          = 5003
+	ErrJoinFleetGroupNumberNotEnough  = 5004
 )
 
 const (
@@ -83,6 +84,8 @@ func GenericErrorText(code int) string {
 		return "Invalid Production type"
 	case ErrMergeShipTypeNotEqual:
 		return "Source and target ship types are not the same"
+	case ErrJoinFleetGroupNumberNotEnough:
+		return "Not enough ships in the group to join a fleet"
 	default:
 		return fmt.Sprintf("Undescribed error with code %d", code)
 	}
diff --git a/pkg/error/generic_test.go b/internal/error/generic_test.go
similarity index 100%
rename from pkg/error/generic_test.go
rename to internal/error/generic_test.go
diff --git a/pkg/error/input.go b/internal/error/input.go
similarity index 93%
rename from pkg/error/input.go
rename to internal/error/input.go
index 1abd291..32ffe7b 100644
--- a/pkg/error/input.go
+++ b/internal/error/input.go
@@ -67,3 +67,7 @@ func NewProductionInvalidError(arg ...any) error {
 func NewMergeShipTypeNotEqualError(arg ...any) error {
 	return newGenericError(ErrMergeShipTypeNotEqual, arg...)
 }
+
+func NewJoinFleetGroupNumberNotEnoughError(arg ...any) error {
+	return newGenericError(ErrJoinFleetGroupNumberNotEnough, arg...)
+}
diff --git a/pkg/error/repo.go b/internal/error/repo.go
similarity index 100%
rename from pkg/error/repo.go
rename to internal/error/repo.go
diff --git a/pkg/error/state.go b/internal/error/state.go
similarity index 100%
rename from pkg/error/state.go
rename to internal/error/state.go
diff --git a/internal/game/cmd_group.go b/internal/game/cmd_group.go
new file mode 100644
index 0000000..ad6f4c6
--- /dev/null
+++ b/internal/game/cmd_group.go
@@ -0,0 +1,22 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func JoinEqualGroups(configure func(*controller.Param), race string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = joinEqualGroups(r, g, race)
+		})
+	})
+	return
+}
+
+func joinEqualGroups(r controller.Repo, g game.Game, race string) error {
+	if err := g.JoinEqualGroups(race); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/internal/game/cmd_group_test.go b/internal/game/cmd_group_test.go
new file mode 100644
index 0000000..ce9b539
--- /dev/null
+++ b/internal/game/cmd_group_test.go
@@ -0,0 +1,17 @@
+package game_test
+
+import (
+	"testing"
+
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestJoinEqualGroups(t *testing.T) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
+		err := game.JoinEqualGroups(p, "race_01")
+		assert.NoError(t, err)
+	})
+}
diff --git a/internal/game/cmd_planet.go b/internal/game/cmd_planet.go
new file mode 100644
index 0000000..8b46619
--- /dev/null
+++ b/internal/game/cmd_planet.go
@@ -0,0 +1,22 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func RenamePlanet(configure func(*controller.Param), race string, number int, name string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = renamePlanet(r, g, race, number, name)
+		})
+	})
+	return
+}
+
+func renamePlanet(r controller.Repo, g game.Game, race string, number int, name string) error {
+	if err := g.RenamePlanet(race, number, name); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/pkg/game/cmd_planet_test.go b/internal/game/cmd_planet_test.go
similarity index 86%
rename from pkg/game/cmd_planet_test.go
rename to internal/game/cmd_planet_test.go
index c513cd7..bade304 100644
--- a/pkg/game/cmd_planet_test.go
+++ b/internal/game/cmd_planet_test.go
@@ -4,16 +4,17 @@ import (
 	"slices"
 	"testing"
 
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	e "github.com/iliadenisov/galaxy/internal/error"
 
 	"github.com/google/uuid"
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestRenamePlanet(t *testing.T) {
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		cg := g()
 		var number int
 		var owner uuid.UUID
diff --git a/internal/game/cmd_production.go b/internal/game/cmd_production.go
new file mode 100644
index 0000000..d245d6c
--- /dev/null
+++ b/internal/game/cmd_production.go
@@ -0,0 +1,22 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func PlanetProduction(configure func(*controller.Param), race string, planetNumber int, prodType, subject string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = planetProduction(r, g, race, planetNumber, prodType, subject)
+		})
+	})
+	return
+}
+
+func planetProduction(r controller.Repo, g game.Game, race string, planetNumber int, prodType, subject string) error {
+	if err := g.PlanetProduction(race, planetNumber, prodType, subject); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/internal/game/cmd_science.go b/internal/game/cmd_science.go
new file mode 100644
index 0000000..e1ef2d9
--- /dev/null
+++ b/internal/game/cmd_science.go
@@ -0,0 +1,38 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func CreateScience(configure func(*controller.Param), race, typeName string, drive, weapons, shields, cargo float64) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = createScience(r, g, race, typeName, drive, weapons, shields, cargo)
+		})
+	})
+	return
+}
+
+func createScience(r controller.Repo, g game.Game, race, typeName string, d, w, s, c float64) error {
+	if err := g.CreateScience(race, typeName, d, w, s, c); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
+
+func DeleteScience(configure func(*controller.Param), race, typeName string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = deleteScience(r, g, race, typeName)
+		})
+	})
+	return
+}
+
+func deleteScience(r controller.Repo, g game.Game, race, typeName string) error {
+	if err := g.DeleteScience(race, typeName); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/pkg/game/cmd_science_test.go b/internal/game/cmd_science_test.go
similarity index 90%
rename from pkg/game/cmd_science_test.go
rename to internal/game/cmd_science_test.go
index d3c2908..4120416 100644
--- a/pkg/game/cmd_science_test.go
+++ b/internal/game/cmd_science_test.go
@@ -4,16 +4,18 @@ import (
 	"strconv"
 	"testing"
 
-	e "github.com/iliadenisov/galaxy/pkg/error"
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/controller"
+
+	e "github.com/iliadenisov/galaxy/internal/error"
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestCreateScience(t *testing.T) {
 	race := "race_01"
 	typeName := "First Step"
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		err := game.DeleteScience(p, race, typeName)
 		assert.ErrorContains(t, err, e.GenericErrorText(e.ErrInputEntityNotExists))
 		err = game.CreateScience(p, unknownRaceName, "  "+typeName+" ", 1, 0, 0, 0) // TODO: test on dead race
@@ -72,7 +74,7 @@ func TestCreateScienceValidation(t *testing.T) {
 		{typeName, 0, 0, 0, -1, e.GenericErrorText(e.ErrInputCargoValue)},
 		{typeName, 0, 1, 1, -1, e.GenericErrorText(e.ErrInputCargoValue)},
 	}
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		for i, tc := range table {
 			if tc.err == "" {
 				err := game.CreateScience(p, race, tc.name+strconv.Itoa(i), tc.d, tc.w, tc.s, tc.c)
diff --git a/internal/game/cmd_ship_type.go b/internal/game/cmd_ship_type.go
new file mode 100644
index 0000000..782a002
--- /dev/null
+++ b/internal/game/cmd_ship_type.go
@@ -0,0 +1,54 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func CreateShipType(configure func(*controller.Param), race, typeName string, drive, weapons, shields, cargo float64, armament int) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = createShipType(r, g, race, typeName, drive, weapons, shields, cargo, armament)
+		})
+	})
+	return
+}
+
+func createShipType(r controller.Repo, g game.Game, race, typeName string, d, w, s, c float64, a int) error {
+	if err := g.CreateShipType(race, typeName, d, w, s, c, a); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
+
+func MergeShipType(configure func(*controller.Param), race, source, target string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = mergeShipType(r, g, race, source, target)
+		})
+	})
+	return
+}
+
+func mergeShipType(r controller.Repo, g game.Game, race, source, target string) error {
+	if err := g.MergeShipType(race, source, target); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
+
+func DeleteShipType(configure func(*controller.Param), race, typeName string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) {
+			err = deleteShipType(r, g, race, typeName)
+		})
+	})
+	return
+}
+
+func deleteShipType(r controller.Repo, g game.Game, race, typeName string) error {
+	if err := g.DeleteShipType(race, typeName); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/pkg/game/cmd_ship_type_test.go b/internal/game/cmd_ship_type_test.go
similarity index 91%
rename from pkg/game/cmd_ship_type_test.go
rename to internal/game/cmd_ship_type_test.go
index d633994..96cdbe7 100644
--- a/pkg/game/cmd_ship_type_test.go
+++ b/internal/game/cmd_ship_type_test.go
@@ -4,16 +4,18 @@ import (
 	"strconv"
 	"testing"
 
-	e "github.com/iliadenisov/galaxy/pkg/error"
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/controller"
+
+	e "github.com/iliadenisov/galaxy/internal/error"
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestCreateShipType(t *testing.T) {
 	race := "race_01"
 	typeName := "Drone"
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		err := game.DeleteShipType(p, race, typeName)
 		assert.ErrorContains(t, err, e.GenericErrorText(e.ErrInputEntityNotExists))
 		err = game.CreateShipType(p, unknownRaceName, "  "+typeName+" ", 1, 0, 0, 0, 0) // TODO: test on dead race
@@ -77,7 +79,7 @@ func TestCreateShipTypeValidation(t *testing.T) {
 		{typeName, 0, 1, 0, 0, 0, e.GenericErrorText(e.ErrInputShipTypeWeaponsAndArmamentValue)},
 		{typeName, 0, 0, 0, 0, 1, e.GenericErrorText(e.ErrInputShipTypeWeaponsAndArmamentValue)},
 	}
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		for i, tc := range table {
 			if tc.err == "" {
 				err := game.CreateShipType(p, race, tc.name+strconv.Itoa(i), tc.d, tc.w, tc.s, tc.c, tc.a)
@@ -94,7 +96,7 @@ func TestCreateShipTypeValidation(t *testing.T) {
 
 func TestMergeShipType(t *testing.T) {
 	race := "race_01"
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		err := game.CreateShipType(p, race, "Drone", 1, 0, 0, 0, 0)
 		assert.NoError(t, err)
 		err = game.CreateShipType(p, race, "Spy", 1, 0, 0, 0, 0)
diff --git a/internal/game/cmd_war_peace.go b/internal/game/cmd_war_peace.go
new file mode 100644
index 0000000..1690d9a
--- /dev/null
+++ b/internal/game/cmd_war_peace.go
@@ -0,0 +1,27 @@
+package game
+
+import (
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func DeclareWar(configure func(*controller.Param), from, to string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) { err = updateRelation(r, g, from, to, game.RelationWar) })
+	})
+	return
+}
+
+func DeclarePeace(configure func(*controller.Param), from, to string) (err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.Execute(func(r controller.Repo, g game.Game) { err = updateRelation(r, g, from, to, game.RelationPeace) })
+	})
+	return
+}
+
+func updateRelation(r controller.Repo, g game.Game, hostRace, opponentRace string, rel game.Relation) error {
+	if err := g.UpdateRelation(hostRace, opponentRace, rel); err != nil {
+		return err
+	}
+	return r.SaveState(g)
+}
diff --git a/pkg/game/cmd_war_peace_test.go b/internal/game/cmd_war_peace_test.go
similarity index 85%
rename from pkg/game/cmd_war_peace_test.go
rename to internal/game/cmd_war_peace_test.go
index 58c4d69..7941f93 100644
--- a/pkg/game/cmd_war_peace_test.go
+++ b/internal/game/cmd_war_peace_test.go
@@ -3,15 +3,16 @@ package game_test
 import (
 	"testing"
 
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	e "github.com/iliadenisov/galaxy/internal/error"
 
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestDeclarePeaceAndWarSingle(t *testing.T) {
-	g(t, func(f func(*game.Param), g func() mg.Game) {
+	g(t, func(f func(*controller.Param), g func() mg.Game) {
 		hostRace := "race_05"
 		opponentRace := "race_01"
 
@@ -37,7 +38,7 @@ func TestDeclarePeaceAndWarSingle(t *testing.T) {
 }
 
 func TestDeclarePeaceAndWarAll(t *testing.T) {
-	g(t, func(f func(*game.Param), g func() mg.Game) {
+	g(t, func(f func(*controller.Param), g func() mg.Game) {
 		hostRace := "race_07"
 
 		for i := range testRaceCount {
diff --git a/internal/game/controller.go b/internal/game/controller.go
new file mode 100644
index 0000000..b4949b7
--- /dev/null
+++ b/internal/game/controller.go
@@ -0,0 +1,28 @@
+package game
+
+import (
+	"github.com/google/uuid"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/game"
+)
+
+func LoadState(configure func(*controller.Param)) (g game.Game, err error) {
+	control(configure, func(c *controller.Ctrl) { c.ExecuteInit(func(r controller.Repo) { g, err = c.Repo.LoadState() }) })
+	return
+}
+
+func GenerateGame(configure func(*controller.Param), races []string) (gameID uuid.UUID, err error) {
+	control(configure, func(c *controller.Ctrl) {
+		c.ExecuteInit(func(r controller.Repo) { gameID, err = controller.NewGame(r, races) })
+	})
+	return
+}
+
+func control(configure func(*controller.Param), consumer func(*controller.Ctrl)) error {
+	c, err := controller.NewController(configure)
+	if err != nil {
+		return err
+	}
+	consumer(c)
+	return nil
+}
diff --git a/pkg/game/controller_test.go b/internal/game/controller_test.go
similarity index 67%
rename from pkg/game/controller_test.go
rename to internal/game/controller_test.go
index e76d074..bb832e1 100644
--- a/pkg/game/controller_test.go
+++ b/internal/game/controller_test.go
@@ -4,9 +4,11 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
-	"github.com/iliadenisov/galaxy/pkg/util"
+	"github.com/iliadenisov/galaxy/internal/controller"
+
+	"github.com/iliadenisov/galaxy/internal/game"
+	mg "github.com/iliadenisov/galaxy/internal/model/game"
+	"github.com/iliadenisov/galaxy/internal/util"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -20,21 +22,21 @@ func raceNum(i int) string {
 }
 
 func TestComposeGame(t *testing.T) {
-	g(t, func(p func(*game.Param), g func() mg.Game) {
+	g(t, func(p func(*controller.Param), g func() mg.Game) {
 		_, err := game.GenerateGame(p, []string{"r1", "r2"})
 		assert.Error(t, err)
 		assert.ErrorContains(t, err, "state for turn 0 already saved")
 	})
 }
 
-func g(t *testing.T, f func(p func(*game.Param), g func() mg.Game)) {
+func g(t *testing.T, f func(p func(*controller.Param), g func() mg.Game)) {
 	root, cleanup := util.CreateWorkDir(t)
 	defer cleanup()
 	races := make([]string, testRaceCount)
 	for i := range testRaceCount {
 		races[i] = raceNum(i)
 	}
-	p := func(p *game.Param) { p.StoragePath = root }
+	p := func(p *controller.Param) { p.StoragePath = root }
 	_, err := game.GenerateGame(p, races)
 	if err != nil {
 		assert.FailNow(t, "g: ComposeGame", err)
diff --git a/pkg/generator/generator.go b/internal/generator/generator.go
similarity index 100%
rename from pkg/generator/generator.go
rename to internal/generator/generator.go
diff --git a/pkg/generator/generator_test.go b/internal/generator/generator_test.go
similarity index 98%
rename from pkg/generator/generator_test.go
rename to internal/generator/generator_test.go
index ccd0251..c80d425 100644
--- a/pkg/generator/generator_test.go
+++ b/internal/generator/generator_test.go
@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/generator"
+	"github.com/iliadenisov/galaxy/internal/generator"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/generator/map.go b/internal/generator/map.go
similarity index 96%
rename from pkg/generator/map.go
rename to internal/generator/map.go
index 5bc042e..86f25cc 100644
--- a/pkg/generator/map.go
+++ b/internal/generator/map.go
@@ -5,7 +5,7 @@ import (
 	"math"
 	"math/rand"
 
-	"github.com/iliadenisov/galaxy/pkg/generator/plotter"
+	"github.com/iliadenisov/galaxy/internal/generator/plotter"
 )
 
 type Map struct {
diff --git a/pkg/generator/map_test.go b/internal/generator/map_test.go
similarity index 91%
rename from pkg/generator/map_test.go
rename to internal/generator/map_test.go
index dd8c054..b03b37f 100644
--- a/pkg/generator/map_test.go
+++ b/internal/generator/map_test.go
@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/number"
+	"github.com/iliadenisov/galaxy/internal/number"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/generator/planet.go b/internal/generator/planet.go
similarity index 100%
rename from pkg/generator/planet.go
rename to internal/generator/planet.go
diff --git a/pkg/generator/planet_test.go b/internal/generator/planet_test.go
similarity index 93%
rename from pkg/generator/planet_test.go
rename to internal/generator/planet_test.go
index 316cbf8..95b16bc 100644
--- a/pkg/generator/planet_test.go
+++ b/internal/generator/planet_test.go
@@ -4,7 +4,7 @@ import (
 	"regexp"
 	"testing"
 
-	g "github.com/iliadenisov/galaxy/pkg/generator"
+	g "github.com/iliadenisov/galaxy/internal/generator"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/generator/plotter/plotter.go b/internal/generator/plotter/plotter.go
similarity index 97%
rename from pkg/generator/plotter/plotter.go
rename to internal/generator/plotter/plotter.go
index 85a642b..25e5a9b 100644
--- a/pkg/generator/plotter/plotter.go
+++ b/internal/generator/plotter/plotter.go
@@ -6,7 +6,7 @@ import (
 	"math"
 	"math/rand"
 
-	"github.com/iliadenisov/galaxy/pkg/bitmap"
+	"github.com/iliadenisov/galaxy/internal/bitmap"
 )
 
 type Plotter struct {
diff --git a/pkg/generator/plotter/plotter_test.go b/internal/generator/plotter/plotter_test.go
similarity index 97%
rename from pkg/generator/plotter/plotter_test.go
rename to internal/generator/plotter/plotter_test.go
index 82ee030..3d7ddd2 100644
--- a/pkg/generator/plotter/plotter_test.go
+++ b/internal/generator/plotter/plotter_test.go
@@ -3,7 +3,7 @@ package plotter_test
 import (
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/generator/plotter"
+	"github.com/iliadenisov/galaxy/internal/generator/plotter"
 )
 
 func TestNewPlotter(t *testing.T) {
diff --git a/pkg/generator/settings.go b/internal/generator/settings.go
similarity index 100%
rename from pkg/generator/settings.go
rename to internal/generator/settings.go
diff --git a/internal/model/game/fleet.go b/internal/model/game/fleet.go
new file mode 100644
index 0000000..c350f52
--- /dev/null
+++ b/internal/model/game/fleet.go
@@ -0,0 +1,102 @@
+package game
+
+import (
+	"math"
+	"slices"
+
+	"github.com/google/uuid"
+	e "github.com/iliadenisov/galaxy/internal/error"
+)
+
+type Fleet struct {
+	ID      uuid.UUID `json:"id"`
+	OwnerID uuid.UUID `json:"ownerId"`
+	Name    string    `json:"name"`
+}
+
+// TODO: Hello! Wanna know fleet's speed? Good. Implement & test this func first.
+func (g Game) FleetSpeed(fl Fleet) float64 {
+	result := math.MaxFloat64
+	for sg := range g.ShipGroups {
+		if g.ShipGroups[sg].FleetID == nil || *g.ShipGroups[sg].FleetID != fl.ID {
+			continue
+		}
+		st := g.mustShipType(g.ShipGroups[sg].TypeID)
+		typeSpeed := g.ShipGroups[sg].Speed(st)
+		if typeSpeed < result {
+			result = typeSpeed
+		}
+	}
+	return result
+}
+
+func (g Game) JoinShipGroupToFleet(raceName, fleetName string, group, count uint) error {
+	ri, err := g.raceIndex(raceName)
+	if err != nil {
+		return err
+	}
+	return g.joinShipGroupToFleetInternal(ri, fleetName, group, count)
+}
+
+func (g Game) joinShipGroupToFleetInternal(ri int, fleetName string, group, count uint) (err error) {
+	name, ok := validateTypeName(fleetName)
+	if !ok {
+		return e.NewEntityTypeNameValidationError("%q", name)
+	}
+	sgi := -1
+	var maxIndex uint
+	for i, sg := range g.listShipGroups(ri) {
+		if sgi < 0 && sg.Index == group {
+			sgi = i
+		}
+		if sg.Index > maxIndex {
+			maxIndex = sg.Index
+		}
+	}
+	if sgi < 0 {
+		return e.NewEntityNotExistsError("group #%d", group)
+	}
+
+	if g.ShipGroups[sgi].Number < count {
+		return e.NewJoinFleetGroupNumberNotEnoughError("%d<%d", g.ShipGroups[sgi].Number, count)
+	}
+
+	fi := g.fleetIndex(ri, name)
+	if fi < 0 {
+		fi, err = g.createFleet(ri, name)
+		if err != nil {
+			return err
+		}
+	}
+
+	if g.ShipGroups[sgi].Number != count && count > 0 {
+		newGroup := g.ShipGroups[sgi]
+		newGroup.Number -= count
+		g.ShipGroups[sgi].Number = count
+		newGroup.Index = maxIndex + 1
+		g.ShipGroups = append(g.ShipGroups, newGroup)
+	}
+
+	g.ShipGroups[sgi].FleetID = &g.Fleets[fi].ID
+	return nil
+}
+
+func (g Game) fleetIndex(ri int, name string) int {
+	return slices.IndexFunc(g.Fleets, func(f Fleet) bool { return f.OwnerID == g.Race[ri].ID && f.Name == name })
+}
+
+func (g Game) createFleet(ri int, name string) (int, error) {
+	n, ok := validateTypeName(name)
+	if !ok {
+		return 0, e.NewEntityTypeNameValidationError("%q", n)
+	}
+	if fl := g.fleetIndex(ri, n); fl >= 0 {
+		return 0, e.NewEntityTypeNameDuplicateError("fleet %w", g.Fleets[fl].Name)
+	}
+	g.Fleets = append(g.Fleets, Fleet{
+		ID:      uuid.New(),
+		OwnerID: g.Race[ri].ID,
+		Name:    n,
+	})
+	return len(g.Fleets) - 1, nil
+}
diff --git a/pkg/model/game/game.go b/internal/model/game/game.go
similarity index 98%
rename from pkg/model/game/game.go
rename to internal/model/game/game.go
index dae1097..1f8e185 100644
--- a/pkg/model/game/game.go
+++ b/internal/model/game/game.go
@@ -6,7 +6,7 @@ import (
 	"strings"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	e "github.com/iliadenisov/galaxy/internal/error"
 )
 
 type Game struct {
diff --git a/pkg/model/game/game_export_test.go b/internal/model/game/game_export_test.go
similarity index 77%
rename from pkg/model/game/game_export_test.go
rename to internal/model/game/game_export_test.go
index 36a67c8..db843e5 100644
--- a/pkg/model/game/game_export_test.go
+++ b/internal/model/game/game_export_test.go
@@ -6,6 +6,6 @@ func (g *Game) CreateShips(ri int, shipTypeName string, planetNumber int, quanti
 	return g.createShips(ri, shipTypeName, planetNumber, quantity)
 }
 
-func (g Game) ListShipGroups(ri int) iter.Seq[ShipGroup] {
+func (g Game) ListShipGroups(ri int) iter.Seq2[int, ShipGroup] {
 	return g.listShipGroups(ri)
 }
diff --git a/pkg/model/game/group.go b/internal/model/game/group.go
similarity index 93%
rename from pkg/model/game/group.go
rename to internal/model/game/group.go
index 9234fce..d77a21c 100644
--- a/pkg/model/game/group.go
+++ b/internal/model/game/group.go
@@ -2,12 +2,13 @@ package game
 
 import (
 	"iter"
+	"maps"
 	"math"
 	"slices"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
-	"github.com/iliadenisov/galaxy/pkg/number"
+	e "github.com/iliadenisov/galaxy/internal/error"
+	"github.com/iliadenisov/galaxy/internal/number"
 )
 
 type CargoType string
@@ -120,7 +121,7 @@ func (g *Game) JoinEqualGroups(raceName string) error {
 }
 
 func (g *Game) joinEqualGroupsInternal(ri int) {
-	shipGroups := slices.Collect(g.listShipGroups(ri))
+	shipGroups := slices.Collect(maps.Values(maps.Collect(g.listShipGroups(ri))))
 	origin := len(shipGroups)
 	if origin < 2 {
 		return
@@ -155,7 +156,7 @@ func (g *Game) createShips(ri int, shipTypeName string, planetNumber int, quanti
 	}
 
 	var maxIndex uint
-	for sg := range g.listShipGroups(ri) {
+	for _, sg := range g.listShipGroups(ri) {
 		if sg.Index > maxIndex {
 			maxIndex = sg.Index
 		}
@@ -175,11 +176,11 @@ func (g *Game) createShips(ri int, shipTypeName string, planetNumber int, quanti
 	return nil
 }
 
-func (g Game) listShipGroups(ri int) iter.Seq[ShipGroup] {
-	return func(yield func(ShipGroup) bool) {
+func (g Game) listShipGroups(ri int) iter.Seq2[int, ShipGroup] {
+	return func(yield func(int, ShipGroup) bool) {
 		for sg := range g.ShipGroups {
 			if g.ShipGroups[sg].OwnerID == g.Race[ri].ID {
-				if !yield(g.ShipGroups[sg]) {
+				if !yield(sg, g.ShipGroups[sg]) {
 					return
 				}
 			}
diff --git a/pkg/model/game/group_test.go b/internal/model/game/group_test.go
similarity index 84%
rename from pkg/model/game/group_test.go
rename to internal/model/game/group_test.go
index c60c0aa..7b57220 100644
--- a/pkg/model/game/group_test.go
+++ b/internal/model/game/group_test.go
@@ -1,14 +1,15 @@
 package game_test
 
 import (
+	"iter"
 	"math/rand/v2"
 	"slices"
 	"testing"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
-	gg "github.com/iliadenisov/galaxy/pkg/game"
-	"github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	e "github.com/iliadenisov/galaxy/internal/error"
+	"github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -296,9 +297,9 @@ func TestJoinEqualGroups(t *testing.T) {
 		Height: 10,
 		Planet: make([]game.Planet, 3),
 	}
-	g.Map.Planet[0] = gg.NewPlanet(0, "Planet_0", g.Race[0].ID, 0, 0, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
-	g.Map.Planet[1] = gg.NewPlanet(1, "Planet_1", g.Race[1].ID, 1, 1, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
-	g.Map.Planet[2] = gg.NewPlanet(1, "Planet_2", g.Race[0].ID, 2, 2, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
+	g.Map.Planet[0] = controller.NewPlanet(0, "Planet_0", g.Race[0].ID, 0, 0, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
+	g.Map.Planet[1] = controller.NewPlanet(1, "Planet_1", g.Race[1].ID, 1, 1, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
+	g.Map.Planet[2] = controller.NewPlanet(1, "Planet_2", g.Race[0].ID, 2, 2, 100, 0, 0, 0, game.ProductionNone.AsType(uuid.Nil))
 
 	err := g.CreateShipType("Race_0", "R0_Gunship", 60, 30, 100, 0, 3)
 	assert.NoError(t, err)
@@ -317,48 +318,48 @@ func TestJoinEqualGroups(t *testing.T) {
 
 	err = g.CreateShips(raceIdx, "R0_Freighter", 0, 1) // 1 -> 2
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 1)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 1)
 
 	err = g.CreateShips(1, "R1_Freighter", 1, 1)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(1)), 1)
+	assert.Len(t, collectGroups(g.ListShipGroups(1)), 1)
 
 	err = g.CreateShips(raceIdx, "R0_Freighter", 0, 6) // (2)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 2)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 2)
 
 	err = g.CreateShips(raceIdx, "R0_Gunship", 0, 2) // (3)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 3)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 3)
 
 	err = g.CreateShips(1, "R1_Gunship", 1, 1)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(1)), 2)
+	assert.Len(t, collectGroups(g.ListShipGroups(1)), 2)
 
 	g.Race[raceIdx].Drive = 1.5
 	err = g.CreateShips(raceIdx, "R0_Gunship", 0, 9) // 4 -> 6
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 4)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 4)
 	err = g.CreateShips(raceIdx, "R0_Freighter", 0, 7) // 5 -> 7
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 5)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 5)
 	err = g.CreateShips(raceIdx, "R0_Gunship", 0, 4) // (6)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 6)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 6)
 	err = g.CreateShips(raceIdx, "R0_Freighter", 0, 4) // (7)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 7)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 7)
 
 	g.Race[1].Shields = 2.0
 	err = g.CreateShips(1, "R1_Freighter", 1, 1)
 	assert.NoError(t, err)
-	assert.Len(t, slices.Collect(g.ListShipGroups(1)), 3)
+	assert.Len(t, collectGroups(g.ListShipGroups(1)), 3)
 
 	err = g.JoinEqualGroups("Race_0")
 	assert.NoError(t, err)
 
-	assert.Len(t, slices.Collect(g.ListShipGroups(1)), 3)
-	assert.Len(t, slices.Collect(g.ListShipGroups(raceIdx)), 4)
+	assert.Len(t, collectGroups(g.ListShipGroups(1)), 3)
+	assert.Len(t, collectGroups(g.ListShipGroups(raceIdx)), 4)
 
 	shipTypeID := func(ri int, name string) uuid.UUID {
 		st := slices.IndexFunc(g.Race[ri].ShipTypes, func(v game.ShipType) bool { return v.Name == name })
@@ -369,7 +370,7 @@ func TestJoinEqualGroups(t *testing.T) {
 		return g.Race[ri].ShipTypes[st].ID
 	}
 
-	for sg := range g.ListShipGroups(raceIdx) {
+	for _, sg := range g.ListShipGroups(raceIdx) {
 		switch {
 		case sg.TypeID == shipTypeID(raceIdx, "R0_Freighter") && sg.Drive == 1.1:
 			assert.Equal(t, uint(7), sg.Number)
@@ -388,3 +389,11 @@ func TestJoinEqualGroups(t *testing.T) {
 		}
 	}
 }
+
+func collectGroups(i iter.Seq2[int, game.ShipGroup]) []game.ShipGroup {
+	result := make([]game.ShipGroup, 0)
+	for _, sg := range i {
+		result = append(result, sg)
+	}
+	return result
+}
diff --git a/pkg/model/game/map.go b/internal/model/game/map.go
similarity index 100%
rename from pkg/model/game/map.go
rename to internal/model/game/map.go
diff --git a/pkg/model/game/planet.go b/internal/model/game/planet.go
similarity index 98%
rename from pkg/model/game/planet.go
rename to internal/model/game/planet.go
index ae4669c..1e82ee9 100644
--- a/pkg/model/game/planet.go
+++ b/internal/model/game/planet.go
@@ -5,7 +5,7 @@ import (
 	"slices"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	e "github.com/iliadenisov/galaxy/internal/error"
 )
 
 type UnidentifiedPlanet struct {
diff --git a/pkg/model/game/production.go b/internal/model/game/production.go
similarity index 98%
rename from pkg/model/game/production.go
rename to internal/model/game/production.go
index 6e4107c..9503059 100644
--- a/pkg/model/game/production.go
+++ b/internal/model/game/production.go
@@ -4,7 +4,7 @@ import (
 	"slices"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	e "github.com/iliadenisov/galaxy/internal/error"
 )
 
 type PlanetProduction string
diff --git a/pkg/model/game/race.go b/internal/model/game/race.go
similarity index 100%
rename from pkg/model/game/race.go
rename to internal/model/game/race.go
diff --git a/pkg/model/game/report.go b/internal/model/game/report.go
similarity index 100%
rename from pkg/model/game/report.go
rename to internal/model/game/report.go
diff --git a/pkg/model/game/science.go b/internal/model/game/science.go
similarity index 98%
rename from pkg/model/game/science.go
rename to internal/model/game/science.go
index 58d1ae9..805df86 100644
--- a/pkg/model/game/science.go
+++ b/internal/model/game/science.go
@@ -4,7 +4,7 @@ import (
 	"slices"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	e "github.com/iliadenisov/galaxy/internal/error"
 )
 
 type Science struct {
@@ -74,6 +74,9 @@ func (g Game) createScienceInternal(ri int, name string, d, w, s, c float64) err
 	if !ok {
 		return e.NewEntityTypeNameValidationError("%q", n)
 	}
+	if sc := slices.IndexFunc(g.Race[ri].Sciences, func(s Science) bool { return s.Name == n }); sc >= 0 {
+		return e.NewEntityTypeNameDuplicateError("science %w", g.Race[ri].Sciences[sc].Name)
+	}
 	if d < 0 {
 		return e.NewDriveValueError(d)
 	}
@@ -90,9 +93,6 @@ func (g Game) createScienceInternal(ri int, name string, d, w, s, c float64) err
 	if sum != 1 {
 		return e.NewScienceSumValuesError("D=%f W=%f S=%f C=%f sum=%f", d, w, s, c, sum)
 	}
-	if sc := slices.IndexFunc(g.Race[ri].Sciences, func(s Science) bool { return s.Name == n }); sc >= 0 {
-		return e.NewEntityTypeNameDuplicateError("science %w", g.Race[ri].Sciences[sc].Name)
-	}
 	g.Race[ri].Sciences = append(g.Race[ri].Sciences, Science{
 		ID: uuid.New(),
 		ScienceReport: ScienceReport{
diff --git a/pkg/model/game/settings.go b/internal/model/game/settings.go
similarity index 100%
rename from pkg/model/game/settings.go
rename to internal/model/game/settings.go
diff --git a/pkg/model/game/ship.go b/internal/model/game/ship.go
similarity index 93%
rename from pkg/model/game/ship.go
rename to internal/model/game/ship.go
index fa4acbf..a3f34c4 100644
--- a/pkg/model/game/ship.go
+++ b/internal/model/game/ship.go
@@ -2,11 +2,10 @@ package game
 
 import (
 	"fmt"
-	"math"
 	"slices"
 
 	"github.com/google/uuid"
-	e "github.com/iliadenisov/galaxy/pkg/error"
+	e "github.com/iliadenisov/galaxy/internal/error"
 )
 
 type ShipTypeReport struct {
@@ -28,11 +27,6 @@ type ShipTypeReportForeign struct {
 	ShipTypeReport
 }
 
-type Fleet struct {
-	OwnerID    uuid.UUID   `json:"ownerId"`
-	ShipGroups []ShipGroup `json:"group"`
-}
-
 func (st ShipType) Equal(o ShipType) bool {
 	return st.Drive == o.Drive &&
 		st.Weapons == o.Weapons &&
@@ -60,18 +54,6 @@ func (st ShipType) ProductionCost() (mat float64, pop float64) {
 	return
 }
 
-// TODO: test this
-func (g Game) FleetSpeed(fl *Fleet) float64 {
-	result := math.MaxFloat64
-	for _, sg := range fl.ShipGroups {
-		st := g.mustShipType(sg.TypeID)
-		if sg.Speed(st) < result {
-			result = sg.Speed(st)
-		}
-	}
-	return result
-}
-
 func (g Game) mustShipType(id uuid.UUID) *ShipType {
 	for ri := range g.Race {
 		if st := slices.IndexFunc(g.Race[ri].ShipTypes, func(st ShipType) bool { return st.ID == id }); st >= 0 {
diff --git a/pkg/model/game/ship_test.go b/internal/model/game/ship_test.go
similarity index 93%
rename from pkg/model/game/ship_test.go
rename to internal/model/game/ship_test.go
index 1ec4d73..a7d8eec 100644
--- a/pkg/model/game/ship_test.go
+++ b/internal/model/game/ship_test.go
@@ -3,7 +3,7 @@ package game_test
 import (
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/model/game"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/number/number.go b/internal/number/number.go
similarity index 100%
rename from pkg/number/number.go
rename to internal/number/number.go
diff --git a/pkg/number/number_test.go b/internal/number/number_test.go
similarity index 100%
rename from pkg/number/number_test.go
rename to internal/number/number_test.go
diff --git a/pkg/repo/fs/fs.go b/internal/repo/fs/fs.go
similarity index 100%
rename from pkg/repo/fs/fs.go
rename to internal/repo/fs/fs.go
diff --git a/pkg/repo/fs/fs_test.go b/internal/repo/fs/fs_test.go
similarity index 98%
rename from pkg/repo/fs/fs_test.go
rename to internal/repo/fs/fs_test.go
index 152bd03..c5c5256 100644
--- a/pkg/repo/fs/fs_test.go
+++ b/internal/repo/fs/fs_test.go
@@ -5,7 +5,7 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/iliadenisov/galaxy/pkg/util"
+	"github.com/iliadenisov/galaxy/internal/util"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/repo/fs/helper_test.go b/internal/repo/fs/helper_test.go
similarity index 100%
rename from pkg/repo/fs/helper_test.go
rename to internal/repo/fs/helper_test.go
diff --git a/pkg/repo/fs/util.go b/internal/repo/fs/util.go
similarity index 100%
rename from pkg/repo/fs/util.go
rename to internal/repo/fs/util.go
diff --git a/pkg/repo/fs/util_test.go b/internal/repo/fs/util_test.go
similarity index 98%
rename from pkg/repo/fs/util_test.go
rename to internal/repo/fs/util_test.go
index 9de9452..5c96b64 100644
--- a/pkg/repo/fs/util_test.go
+++ b/internal/repo/fs/util_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"
 
 	"github.com/google/uuid"
-	"github.com/iliadenisov/galaxy/pkg/util"
+	"github.com/iliadenisov/galaxy/internal/util"
 	"github.com/stretchr/testify/assert"
 )
 
diff --git a/pkg/repo/game.go b/internal/repo/game.go
similarity index 96%
rename from pkg/repo/game.go
rename to internal/repo/game.go
index c435caf..37273e6 100644
--- a/pkg/repo/game.go
+++ b/internal/repo/game.go
@@ -11,7 +11,7 @@ package repo
 import (
 	"fmt"
 
-	"github.com/iliadenisov/galaxy/pkg/model/game"
+	"github.com/iliadenisov/galaxy/internal/model/game"
 )
 
 const (
diff --git a/pkg/repo/repo.go b/internal/repo/repo.go
similarity index 92%
rename from pkg/repo/repo.go
rename to internal/repo/repo.go
index 3824967..29d9bf5 100644
--- a/pkg/repo/repo.go
+++ b/internal/repo/repo.go
@@ -4,8 +4,8 @@ import (
 	"encoding"
 	"errors"
 
-	e "github.com/iliadenisov/galaxy/pkg/error"
-	"github.com/iliadenisov/galaxy/pkg/repo/fs"
+	e "github.com/iliadenisov/galaxy/internal/error"
+	"github.com/iliadenisov/galaxy/internal/repo/fs"
 )
 
 func NewStorageError(err error) error {
diff --git a/pkg/util/fs.go b/internal/util/fs.go
similarity index 100%
rename from pkg/util/fs.go
rename to internal/util/fs.go
diff --git a/pkg/game/cmd_group.go b/pkg/game/cmd_group.go
deleted file mode 100644
index a11372d..0000000
--- a/pkg/game/cmd_group.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func JoinEqualGroups(configure func(*Param), race string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = joinEqualGroups(r, g, race)
-		})
-	})
-	return
-}
-
-func joinEqualGroups(r Repo, g game.Game, race string) error {
-	if err := g.JoinEqualGroups(race); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/cmd_group_test.go b/pkg/game/cmd_group_test.go
deleted file mode 100644
index f2d40f3..0000000
--- a/pkg/game/cmd_group_test.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package game_test
-
-import (
-	"testing"
-
-	"github.com/iliadenisov/galaxy/pkg/game"
-	mg "github.com/iliadenisov/galaxy/pkg/model/game"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestJoinEqualGroups(t *testing.T) {
-	g(t, func(p func(*game.Param), g func() mg.Game) {
-		err := game.JoinEqualGroups(p, "race_01")
-		assert.NoError(t, err)
-	})
-}
diff --git a/pkg/game/cmd_planet.go b/pkg/game/cmd_planet.go
deleted file mode 100644
index 3491550..0000000
--- a/pkg/game/cmd_planet.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func RenamePlanet(configure func(*Param), race string, number int, name string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = renamePlanet(r, g, race, number, name)
-		})
-	})
-	return
-}
-
-func renamePlanet(r Repo, g game.Game, race string, number int, name string) error {
-	if err := g.RenamePlanet(race, number, name); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/cmd_production.go b/pkg/game/cmd_production.go
deleted file mode 100644
index 8d9aa0c..0000000
--- a/pkg/game/cmd_production.go
+++ /dev/null
@@ -1,19 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func PlanetProduction(configure func(*Param), race string, planetNumber int, prodType, subject string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = planetProduction(r, g, race, planetNumber, prodType, subject)
-		})
-	})
-	return
-}
-
-func planetProduction(r Repo, g game.Game, race string, planetNumber int, prodType, subject string) error {
-	if err := g.PlanetProduction(race, planetNumber, prodType, subject); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/cmd_science.go b/pkg/game/cmd_science.go
deleted file mode 100644
index 70040e3..0000000
--- a/pkg/game/cmd_science.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func CreateScience(configure func(*Param), race, typeName string, drive, weapons, shields, cargo float64) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = createScience(r, g, race, typeName, drive, weapons, shields, cargo)
-		})
-	})
-	return
-}
-
-func createScience(r Repo, g game.Game, race, typeName string, d, w, s, c float64) error {
-	if err := g.CreateScience(race, typeName, d, w, s, c); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
-
-func DeleteScience(configure func(*Param), race, typeName string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = deleteScience(r, g, race, typeName)
-		})
-	})
-	return
-}
-
-func deleteScience(r Repo, g game.Game, race, typeName string) error {
-	if err := g.DeleteScience(race, typeName); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/cmd_ship_type.go b/pkg/game/cmd_ship_type.go
deleted file mode 100644
index d2f6fe3..0000000
--- a/pkg/game/cmd_ship_type.go
+++ /dev/null
@@ -1,51 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func CreateShipType(configure func(*Param), race, typeName string, drive, weapons, shields, cargo float64, armament int) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = createShipType(r, g, race, typeName, drive, weapons, shields, cargo, armament)
-		})
-	})
-	return
-}
-
-func createShipType(r Repo, g game.Game, race, typeName string, d, w, s, c float64, a int) error {
-	if err := g.CreateShipType(race, typeName, d, w, s, c, a); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
-
-func MergeShipType(configure func(*Param), race, source, target string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = mergeShipType(r, g, race, source, target)
-		})
-	})
-	return
-}
-
-func mergeShipType(r Repo, g game.Game, race, source, target string) error {
-	if err := g.MergeShipType(race, source, target); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
-
-func DeleteShipType(configure func(*Param), race, typeName string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) {
-			err = deleteShipType(r, g, race, typeName)
-		})
-	})
-	return
-}
-
-func deleteShipType(r Repo, g game.Game, race, typeName string) error {
-	if err := g.DeleteShipType(race, typeName); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/cmd_war_peace.go b/pkg/game/cmd_war_peace.go
deleted file mode 100644
index 91a7b73..0000000
--- a/pkg/game/cmd_war_peace.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-func DeclareWar(configure func(*Param), from, to string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) { err = updateRelation(r, g, from, to, game.RelationWar) })
-	})
-	return
-}
-
-func DeclarePeace(configure func(*Param), from, to string) (err error) {
-	control(configure, func(c *ctrl) {
-		c.execute(func(r Repo, g game.Game) { err = updateRelation(r, g, from, to, game.RelationPeace) })
-	})
-	return
-}
-
-func updateRelation(r Repo, g game.Game, hostRace, opponentRace string, rel game.Relation) error {
-	if err := g.UpdateRelation(hostRace, opponentRace, rel); err != nil {
-		return err
-	}
-	return r.SaveState(g)
-}
diff --git a/pkg/game/controller.go b/pkg/game/controller.go
deleted file mode 100644
index d56dfcd..0000000
--- a/pkg/game/controller.go
+++ /dev/null
@@ -1,74 +0,0 @@
-package game
-
-import (
-	"fmt"
-
-	"github.com/google/uuid"
-	"github.com/iliadenisov/galaxy/pkg/model/game"
-	"github.com/iliadenisov/galaxy/pkg/repo"
-)
-
-type ctrl struct {
-	param Param
-	repo  Repo
-}
-
-type Param struct {
-	StoragePath string
-}
-
-func LoadState(configure func(*Param)) (g game.Game, err error) {
-	control(configure, func(c *ctrl) { c.executeInit(func(r Repo) { g, err = c.repo.LoadState() }) })
-	return
-}
-
-func GenerateGame(configure func(*Param), races []string) (gameID uuid.UUID, err error) {
-	control(configure, func(c *ctrl) { c.executeInit(func(r Repo) { gameID, err = newGame(r, races) }) })
-	return
-}
-
-func newController(configure func(*Param)) (*ctrl, error) {
-	c := &Param{
-		StoragePath: ".",
-	}
-	if configure != nil {
-		configure(c)
-	}
-	r, err := repo.NewFileRepo(c.StoragePath)
-	if err != nil {
-		return nil, err
-	}
-	return &ctrl{
-		param: *c,
-		repo:  r,
-	}, nil
-}
-
-func control(configure func(*Param), consumer func(*ctrl)) error {
-	c, err := newController(configure)
-	if err != nil {
-		return err
-	}
-	consumer(c)
-	return nil
-}
-
-func (c *ctrl) executeInit(consumer func(Repo)) error {
-	if err := c.repo.Lock(); err != nil {
-		return fmt.Errorf("execute: lock failed: %s", err)
-	}
-	consumer(c.repo)
-	return c.repo.Release()
-}
-
-func (c *ctrl) execute(consumer func(Repo, game.Game)) error {
-	if err := c.repo.Lock(); err != nil {
-		return fmt.Errorf("execute: lock failed: %s", err)
-	}
-	g, err := c.repo.LoadState()
-	if err != nil {
-		return err
-	}
-	consumer(c.repo, g)
-	return c.repo.Release()
-}
diff --git a/pkg/game/game.go b/pkg/game/game.go
deleted file mode 100644
index 954d423..0000000
--- a/pkg/game/game.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package game
-
-import "github.com/iliadenisov/galaxy/pkg/model/game"
-
-type Repo interface {
-	// Lock must be called before any repository operations
-	Lock() error
-
-	// Release must be called after first and only repository operation
-	Release() error
-
-	// SaveTurn stores just generated new turn
-	SaveTurn(uint, game.Game) error
-
-	// SaveState stores current game state updated between turns
-	SaveState(game.Game) error
-
-	// LoadState retrieves game current state
-	LoadState() (game.Game, error)
-}
diff --git a/pkg/model/command/command.go b/pkg/model/command/command.go
deleted file mode 100644
index 820a173..0000000
--- a/pkg/model/command/command.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package command
-
-type Command struct {
-	FromRace string
-}
-
-type CommandAlly struct {
-	Command
-	ToRace string
-}
-
-type CommandWar struct {
-	Command
-	ToRace string
-}