diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..42f3349
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/iliadenisov/galaxy
+
+go 1.20
diff --git a/pkg/generator/draw/draw.go b/pkg/generator/draw/draw.go
new file mode 100644
index 0000000..da72c26
--- /dev/null
+++ b/pkg/generator/draw/draw.go
@@ -0,0 +1,148 @@
+package draw
+
+import (
+	"fmt"
+	"math"
+)
+
+const batchSize = 32
+
+type Plane struct {
+	Width  uint
+	Height uint
+	pixels []uint32
+}
+
+func (p *Plane) pixelsValue() []uint32 {
+	return p.pixels
+}
+
+func New(width uint, height uint) Plane {
+	elements := int(math.Ceil(float64(width*height) / batchSize))
+	return Plane{Width: width, Height: height, pixels: make([]uint32, elements)}
+}
+
+func (p Plane) Mark(x, y int) {
+	boundX := (p.Width + uint(x)) % p.Width
+	boundY := (p.Height + uint(y)) % p.Height
+	p.mark(boundX + boundY*p.Width)
+
+	// p.mark(x + y*p.Width)
+
+	// number := x + y*p.width
+	// index := number / batchSize
+	// bit := number % batchSize
+	// p.pixels[index] |= (0b1 << bit)
+}
+
+func (p Plane) mark(number uint) {
+	// index := number / batchSize
+	// bit := number % batchSize
+	p.pixels[number/batchSize] |= (0b1 << (number % batchSize))
+}
+
+func (p Plane) Marked(x, y uint) bool {
+	return p.marked(x + y*p.Width)
+	// number := x + y*p.width
+	// index := number / batchSize
+	// bit := number % batchSize
+	// return p.pixels[index]&(0b1<<bit) > 0
+}
+
+func (p Plane) marked(number uint) bool {
+	// index := number / batchSize
+	// bit := number % batchSize
+	return p.pixels[number/batchSize]&(0b1<<(number%batchSize)) > 0
+}
+
+func (p Plane) Circle(x, y int, r float64) {
+	plotX := 0
+	plotY := int(math.Ceil(r))
+	delta := 3 - 2*plotY
+	lastY := plotY
+	for plotX <= plotY {
+		p.octant(x, y, plotX, plotY)
+		if plotY < lastY {
+			for lineX := 0; lineX < plotX; lineX++ {
+				p.octant(x, y, lineX, plotY)
+			}
+			lastY = plotY
+		}
+		if delta < 0 {
+			delta += 4*plotX + 6
+		} else {
+			delta += 4*(plotX-plotY) + 10
+			plotY -= 1
+		}
+		plotX += 1
+	}
+	for fillX := 0; fillX < plotX; fillX++ {
+		for fillY := 0; fillY <= fillX; fillY++ {
+			p.octant(x, y, fillX, fillY)
+		}
+	}
+}
+
+func (p Plane) CircleAdjacent(x, y int, r float64) {
+	plotX := 0
+	plotY := int(math.Ceil(r))
+	delta := 1 - 2*plotY
+	err := 0
+	for plotX <= plotY {
+		p.octant(x, y, plotX, plotY)
+		err = 2*(delta+plotY) - 1
+		if delta < 0 && err <= 0 {
+			plotX += 1
+			delta += 2*plotX + 1
+			continue
+		}
+		if delta > 0 && err > 0 {
+			plotY -= 1
+			delta -= 2*plotY + 1
+			continue
+		}
+		plotX += 1
+		plotY -= 1
+		delta += 2 * (plotX - plotY)
+	}
+}
+
+func (p Plane) octant(x, y int, plotX, plotY int) {
+	p.Mark(x+plotX, y+plotY)
+	p.Mark(x+plotX, y-plotY)
+	p.Mark(x-plotX, y+plotY)
+	p.Mark(x-plotX, y-plotY)
+	p.Mark(x+plotY, y+plotX)
+	p.Mark(x+plotY, y-plotX)
+	p.Mark(x-plotY, y+plotX)
+	p.Mark(x-plotY, y-plotX)
+}
+
+func (p Plane) Clear() {
+	for i := range p.pixels {
+		p.pixels[i] &= 0
+	}
+}
+
+func (p Plane) String() string {
+	px := map[bool]string{true: "x", false: "_"}
+	var result string
+	// for y := 0; y < int(p.height); y++ {
+	// 	for x := 0; x < int(p.width); x++ {
+	// 		result += px[p.Marked(uint(x), uint(y))] + " "
+	// 	}
+	// 	result += "\n"
+	// }
+	// result += "\n"
+	cnt := 0
+	for i := 0; i < len(p.pixels); i++ {
+		for bit := 0; bit < batchSize && cnt < int(p.Width*p.Height); bit++ {
+			result += fmt.Sprintf("%s ", px[p.pixels[i]&(0b1<<bit) > 0])
+			cnt++
+			if cnt%int(p.Width) == 0 {
+				result += "\n"
+			}
+		}
+	}
+	return result
+}
diff --git a/pkg/generator/draw/draw_test.go b/pkg/generator/draw/draw_test.go
new file mode 100644
index 0000000..0a60269
--- /dev/null
+++ b/pkg/generator/draw/draw_test.go
@@ -0,0 +1,82 @@
+package draw_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/iliadenisov/galaxy/pkg/generator/draw"
+)
+
+func Test_CreatePlot(t *testing.T) {
+	var pane = draw.New(10, 10)
+	if len(draw.PixelsHolder(&pane)) != 4 {
+		t.Errorf("wrong Pane data size, expected: %d given: %d", 4, len(draw.PixelsHolder(&pane)))
+	}
+
+	pane = draw.New(1, 1)
+	if len(draw.PixelsHolder(&pane)) != 1 {
+		t.Errorf("wrong Pane data size, expected: %d given: %d", 4, len(draw.PixelsHolder(&pane)))
+	}
+
+	pane = draw.New(32, 32)
+	if len(draw.PixelsHolder(&pane)) != 32 {
+		t.Errorf("wrong Pane data size, expected: %d given: %d", 4, len(draw.PixelsHolder(&pane)))
+	}
+}
+
+func Test_Mark(t *testing.T) {
+	var size int = 7
+	var pane = draw.New(uint(size), uint(size))
+	for i := 0; i < int(size); i++ {
+		pane.Mark(0, i)
+		pane.Mark(i, 0)
+		pane.Mark(size-1, i)
+		pane.Mark(i, size-1)
+		pane.Mark(i, i)
+		pane.Mark(size-1-i, i)
+	}
+
+	pixelsHolder := draw.PixelsHolder(&pane)
+
+	if len(pixelsHolder) != 2 {
+		t.Errorf("expected len: %d given: %d", 2, len(pixelsHolder))
+	}
+
+	// if !pane.Marked(0, 0) {
+	// 	t.Errorf("should be marked at x=%d y=%d", 0, 0)
+	// }
+
+	fmt.Println(pane)
+}
+
+func Test_Cleat(t *testing.T) {
+	var pane = draw.New(10, 10)
+	pane.Mark(5, 5)
+	pane.Mark(0, 0)
+	pane.Mark(9, 9)
+	if !pane.Marked(0, 0) {
+		t.Errorf("should be marked at x=%d y=%d", 0, 0)
+	}
+	if !pane.Marked(5, 5) {
+		t.Errorf("should be marked at x=%d y=%d", 5, 5)
+	}
+	if !pane.Marked(9, 9) {
+		t.Errorf("should be marked at x=%d y=%d", 9, 9)
+	}
+	pane.Clear()
+	for _, holder := range draw.PixelsHolder(&pane) {
+		if holder != 0 {
+			t.Errorf("should be all bits clear")
+		}
+	}
+}
+
+func Test_Circle(t *testing.T) {
+	var size int = 40
+	var pane1 = draw.New(uint(size), uint(size))
+	pane1.Circle(size/2+5, size/2-5, float64(size/2)-3)
+	fmt.Println(pane1)
+	var pane2 = draw.New(uint(size), uint(size))
+	pane2.CircleAdjacent(size/2+20, size/2, float64(size/2)-5)
+	// fmt.Println(pane2)
+}
diff --git a/pkg/generator/draw/export_test.go b/pkg/generator/draw/export_test.go
new file mode 100644
index 0000000..1c71f99
--- /dev/null
+++ b/pkg/generator/draw/export_test.go
@@ -0,0 +1,3 @@
+package draw
+
+var PixelsHolder = (*Plane).pixelsValue
diff --git a/pkg/generator/generator.go b/pkg/generator/generator.go
new file mode 100644
index 0000000..3d5778b
--- /dev/null
+++ b/pkg/generator/generator.go
@@ -0,0 +1,160 @@
+package generator
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"math/rand"
+
+	"github.com/iliadenisov/galaxy/pkg/generator/draw"
+)
+
+type Map struct {
+	Width       uint
+	Height      uint
+	HomePlanets []PlanetarySystem
+	FreePlanets []Planet
+	plotter     Plotter
+}
+
+type Coordinate struct {
+	X, Y float64
+}
+
+type Planet struct {
+	Position  Coordinate
+	Size      float64
+	Resources float64 // Сырьё
+}
+
+type PlanetarySystem struct {
+	HW Planet
+	DW []Planet
+}
+
+type Plotter struct {
+	factor  float64
+	sectors draw.Plane
+}
+
+func Generate(param MapParameters) (result Map) {
+	pl := func(c Coordinate, param UninhabitedPlanetParameters) Planet {
+		return Planet{
+			Position:  c,
+			Size:      param.MinSize + rand.Float64()*(param.MaxSize-param.MinSize),
+			Resources: float64(param.MinResource) + rand.Float64()*(param.MaxResource-param.MinResource)}
+	}
+	// mapSize := uint(math.Ceil(math.Sqrt(float64(param.Players)))) * param.HW_MinDistance
+	var mapSize uint = 200
+
+	result = NewMap(mapSize, mapSize, param.Players)
+
+	totalPlanets := param.Players * 10
+	freePlanets := totalPlanets - param.Players*(param.DW_Count+1)
+
+	fmt.Println("map:", mapSize, "players:", param.Players, "planets:", totalPlanets, "uninhabited:", freePlanets)
+
+	giantsNum := int(math.Ceil(float64(freePlanets) * param.GiantPlanets.Probability))
+	fmt.Println("generating", giantsNum, "giant planets")
+	for i := 0; i < giantsNum; i++ {
+		coord := result.newPlanet(float64(param.GiantPlanets.MinDistanceHW))
+		planet := pl(coord, param.GiantPlanets)
+		result.addPlanet(planet)
+		// result.FreePlanets = append(result.FreePlanets, planet)
+	}
+
+	bigsNum := int(math.Ceil(float64(freePlanets) * param.BigPlanets.Probability))
+	fmt.Println("generating", bigsNum, "big planets")
+	for i := 0; i < bigsNum; i++ {
+		coord := result.newPlanet(float64(param.BigPlanets.MinDistanceHW))
+		planet := pl(coord, param.BigPlanets)
+		result.addPlanet(planet)
+		// result.FreePlanets = append(result.FreePlanets, planet)
+	}
+
+	for player := 0; player < int(param.Players); player++ {
+		fmt.Println("generating HW #", player)
+		coord := result.newPlanet(float64(param.HW_MinDistance))
+		planet := Planet{Position: coord, Size: float64(param.HW_Size), Resources: float64(param.HW_Resources)}
+		// fmt.Println("HW: ", planet)
+		result.HomePlanets[player] = PlanetarySystem{HW: planet}
+	}
+
+	fmt.Println("free sectors left: ", len(result.plotter.freeSectors()))
+
+	result.plotter.sectors.Clear()
+
+	for _, hw := range result.HomePlanets {
+		result.plotter.markNoGoZone(hw.HW.Position.X, hw.HW.Position.Y, 5)
+		for _, dw := range hw.DW {
+			result.plotter.markNoGoZone(dw.Position.X, dw.Position.Y, 5)
+		}
+	}
+
+	for _, planet := range result.FreePlanets {
+		result.plotter.markNoGoZone(planet.Position.X, planet.Position.Y, 5)
+
+	}
+
+	fmt.Println("free sectors after reset: ", len(result.plotter.freeSectors()))
+
+	return
+}
+
+func (m Map) newPlanet(deadZoneRaduis float64) Coordinate {
+	fs := m.plotter.freeSectors()
+	fmt.Println("free sectors: ", len(fs))
+	fsCount := len(fs)
+	if fsCount == 0 {
+		panic("no more space for planets")
+	}
+	next := rand.Intn(fsCount)
+	x := fs[next][0]
+	y := fs[next][1]
+	fmt.Println("planet on plot: x =", x, "y =", y)
+	planetX := float64(x)*m.plotter.factor + rand.Float64()*m.plotter.factor
+	planetY := float64(y)*m.plotter.factor + rand.Float64()*m.plotter.factor
+	m.plotter.markDeadZone(int(x), int(y), deadZoneRaduis)
+	return Coordinate{X: planetX, Y: planetY}
+}
+
+func (m *Map) addPlanet(planet Planet) {
+	m.FreePlanets = append(m.FreePlanets, planet)
+}
+
+func (p Plotter) freeSectors() (result [][]uint) {
+	result = make([][]uint, 0)
+	for x := uint(0); x < p.sectors.Width; x++ {
+		for y := uint(0); y < p.sectors.Height; y++ {
+			if !p.sectors.Marked(x, y) {
+				result = append(result, []uint{x, y})
+			}
+		}
+	}
+	return
+}
+
+func (p Plotter) markDeadZone(x, y int, radius float64) {
+	p.sectors.Circle(x, y, radius)
+}
+
+func (p Plotter) markNoGoZone(x, y float64, radius float64) { // TODO: test
+	p.markDeadZone(int(x/p.factor), int(y/p.factor), radius)
+}
+
+func NewMap(width, height, players uint) Map {
+	var factor float64 = 1.0
+	sectorsX := uint(float64(width) / factor)
+	sectorsY := uint(float64(height) / factor)
+	return Map{
+		Width:       width,
+		Height:      height,
+		HomePlanets: make([]PlanetarySystem, players),
+		plotter: Plotter{
+			factor:  factor,
+			sectors: draw.New(sectorsX, sectorsY)}}
+}
+
+func errfmt(message string) error {
+	return errors.New("generator: " + message)
+}
diff --git a/pkg/generator/generator_test.go b/pkg/generator/generator_test.go
new file mode 100644
index 0000000..9e61687
--- /dev/null
+++ b/pkg/generator/generator_test.go
@@ -0,0 +1,11 @@
+package generator_test
+
+import (
+	"testing"
+
+	"github.com/iliadenisov/galaxy/pkg/generator"
+)
+
+func Test_Generator(t *testing.T) {
+	generator.Generate(generator.DefaultMapParameters())
+}
diff --git a/pkg/generator/map_parameter.go b/pkg/generator/map_parameter.go
new file mode 100644
index 0000000..e878de1
--- /dev/null
+++ b/pkg/generator/map_parameter.go
@@ -0,0 +1,82 @@
+package generator
+
+type MapParameters struct {
+	Players        uint
+	HW_Size        uint
+	HW_Resources   uint
+	HW_MinDistance uint
+	DW_Count       uint
+	DW_Size        uint
+	DW_Resources   uint
+	DW_MinDistance uint
+	DW_MaxDistance uint
+
+	GiantPlanets  UninhabitedPlanetParameters
+	BigPlanets    UninhabitedPlanetParameters
+	NormalPlanets UninhabitedPlanetParameters
+	RichPlanets   UninhabitedPlanetParameters
+	Asterioids    UninhabitedPlanetParameters
+}
+
+type UninhabitedPlanetParameters struct {
+	MinDistanceHW uint
+	MinSize       float64
+	MaxSize       float64
+	MinResource   float64
+	MaxResource   float64
+	Probability   float64
+}
+
+func DefaultMapParameters() MapParameters {
+	return MapParameters{
+		Players:        25,
+		HW_Size:        1000,
+		HW_Resources:   10,
+		HW_MinDistance: 30,
+		DW_Count:       2,
+		DW_Size:        500,
+		DW_Resources:   10,
+		DW_MinDistance: 5,
+		DW_MaxDistance: 15,
+		GiantPlanets: UninhabitedPlanetParameters{
+			MinDistanceHW: 20,
+			MinSize:       1500,
+			MaxSize:       2500,
+			MinResource:   0,
+			MaxResource:   3,
+			Probability:   0.06,
+		},
+		BigPlanets: UninhabitedPlanetParameters{
+			MinDistanceHW: 10,
+			MinSize:       1000,
+			MaxSize:       2000,
+			MinResource:   1,
+			MaxResource:   10,
+			Probability:   0.18,
+		},
+		NormalPlanets: UninhabitedPlanetParameters{
+			MinDistanceHW: 0,
+			MinSize:       0.001,
+			MaxSize:       1000,
+			MinResource:   0,
+			MaxResource:   10,
+			Probability:   0.5,
+		},
+		RichPlanets: UninhabitedPlanetParameters{
+			MinDistanceHW: 0,
+			MinSize:       0.001,
+			MaxSize:       500,
+			MinResource:   5,
+			MaxResource:   25,
+			Probability:   0.18,
+		},
+		Asterioids: UninhabitedPlanetParameters{
+			MinDistanceHW: 0,
+			MinSize:       0.001,
+			MaxSize:       10,
+			MinResource:   0,
+			MaxResource:   0,
+			Probability:   0.08,
+		},
+	}
+}
diff --git a/pkg/server/game.go b/pkg/server/game.go
new file mode 100644
index 0000000..47ff4c5
--- /dev/null
+++ b/pkg/server/game.go
@@ -0,0 +1,221 @@
+package server
+
+import "math"
+
+type GameIdentifier string
+type RaceIdentifier string
+
+type Game struct {
+	Id       GameIdentifier
+	Name     string
+	Schedule string // TODO: implement somehow
+	Turn     uint
+	Races    []Race
+	Planets  []Planet
+	warState map[uint]uint
+}
+
+type Race struct {
+	Id      RaceIdentifier
+	Name    string
+	Drive   float64
+	Weapons float64
+	Shields float64
+	Cargo   float64
+	Planets []Planet
+}
+
+func (r Race) FlightDistance() float64 {
+	return r.Drive * 40
+}
+
+func (r Race) VisibilityDistance() float64 {
+	return r.Drive * 30
+}
+
+type Coordinate struct {
+	X, Y float64
+}
+
+type Planet struct {
+	Number     uint
+	Name       string
+	Position   Coordinate
+	Size       float64
+	Production string  // TODO: kinda enum
+	Resources  float64 // Сырьё
+	Industry   float64 // Промышленность
+	Population float64 // Население
+
+	Capital   float64 // CAP $ - Запасы промышленности
+	Material  float64 // MAT M - Запасы сырья
+	Colonists float64 // COL C - Количество колонистов
+	// Параметр "L" означает количество свободных производственных единиц.
+}
+
+// Производственный потенциал (I)
+// промышленность * 0.75 + население * 0.25
+func (p Planet) ProductionCapacity() float64 {
+	return p.Industry*0.75 + p.Population*0.25
+}
+
+// Производство промышленности
+// TODO: test on real values
+func (p *Planet) IncreaseIndustry() {
+	prod := p.ProductionCapacity() / 5
+	industryIncrement := math.Min(prod, p.Material)
+	p.Industry += industryIncrement
+	if p.Industry > p.Population {
+		p.Industry = p.Population
+		p.Capital += p.Population - p.Industry
+	}
+}
+
+// Производство материалов
+// TODO: test on real values
+func (p *Planet) IncreaseMaterial() {
+	p.Material += p.ProductionCapacity() * p.Industry
+}
+
+// Автоматическое увеличение населения на каждом ходу
+func (p *Planet) IncreasePopulation() {
+	p.Population *= 1.08
+	var extraPopulation = p.Size - p.Population
+	if extraPopulation > 0 {
+		p.Colonists += extraPopulation / 8
+		p.Population -= extraPopulation
+	}
+}
+
+type Science struct {
+	Name    string
+	Drive   float64
+	Weapons float64
+	Shields float64
+	Cargo   float64
+}
+
+type ShipType struct {
+	Name     string
+	Drive    float64 // [0], [1...]
+	Armament uint
+	Weapons  float64 // [0], [1...]
+	Shields  float64 // [0], [1...]
+	Cargo    float64 // [0], [1...]
+}
+
+// TODO: test on real values
+func (st ShipType) EmptyMass() float64 {
+	shipMass := st.DriveMass() + st.ShieldsMass() + st.CargoMass() + st.WeaponsMass()
+	return shipMass
+}
+
+func (st ShipType) DriveMass() float64 {
+	return st.Drive
+}
+
+func (st ShipType) ShieldsMass() float64 {
+	return st.Shields
+}
+
+func (st ShipType) CargoMass() float64 {
+	return st.Cargo
+}
+
+func (st ShipType) WeaponsMass() float64 {
+	return float64(st.Armament)*(st.Weapons/2) + st.Weapons/2
+}
+
+type ShipGroup struct {
+	Type    ShipType
+	Number  uint
+	State   string  // TODO: kinda enum: In_Orbit, In_Space, Transfer_State, Upgrade
+	Load    float64 // Cargo loaded - "Масса груза"
+	Drive   float64
+	Weapons float64
+	Shields float64
+	Cargo   float64
+}
+
+// Грузоподъёмность
+func (sg ShipGroup) CargoCapacity() float64 {
+	return sg.Drive * (sg.Type.Cargo + (sg.Type.Cargo*sg.Type.Cargo)/20)
+}
+
+// "Масса перевозимого груза"
+func (sg ShipGroup) CarryingMass() float64 {
+	return sg.Load / sg.Cargo
+}
+
+func (sg ShipGroup) FullMass() float64 {
+	return sg.Type.EmptyMass() + sg.CarryingMass()
+}
+
+// "Эффективность двигателя"
+// равна мощности Двигателей умноженной на текущий технологический уровень блока Двигателей
+func (sg ShipGroup) DriveEffective() float64 {
+	return sg.Type.Drive * sg.Drive
+}
+
+// TODO: test this
+func (sg ShipGroup) Speed() float64 {
+	return sg.DriveEffective() * 20 / sg.FullMass()
+}
+
+func (sg ShipGroup) UpgradeDriveCost(drive float64) float64 {
+	return (1 - sg.Drive/drive) * 10 * sg.Type.Drive
+}
+
+// TODO: test on other values
+func (sg ShipGroup) UpgradeWeaponsCost(weapons float64) float64 {
+	return (1 - sg.Weapons/weapons) * 10 * sg.Type.WeaponsMass()
+}
+
+func (sg ShipGroup) UpgradeShieldsCost(shields float64) float64 {
+	return (1 - sg.Shields/shields) * 10 * sg.Type.Shields
+}
+
+func (sg ShipGroup) UpgradeCargoCost(cargo float64) float64 {
+	return (1 - sg.Cargo/cargo) * 10 * sg.Type.Cargo
+}
+
+// Мощность бомбардировки
+// TODO: maybe rounding must be done only for display?
+func (sg ShipGroup) BombingPower() float64 {
+	// return math.Sqrt(sg.Type.Weapons * sg.Weapons)
+	result := (math.Sqrt(sg.Type.Weapons*sg.Weapons)/10. + 1.) *
+		sg.Type.Weapons *
+		sg.Weapons *
+		float64(sg.Type.Armament) *
+		float64(sg.Number)
+	return toFixed3(result)
+}
+
+type Fleet struct {
+	ShipGroups []ShipGroup
+}
+
+// TODO: test this
+func (fl Fleet) Speed() float64 {
+	result := math.MaxFloat64
+	for _, sg := range fl.ShipGroups {
+		if sg.Speed() < result {
+			result = sg.Speed()
+		}
+	}
+	return result
+}
+
+func round(num float64) int {
+	return int(num + math.Copysign(0.5, num))
+}
+
+// TODO: move to more common place
+func toFixed(num float64, precision int) float64 {
+	output := math.Pow(10, float64(precision))
+	return float64(round(num*output)) / output
+}
+
+func toFixed3(num float64) float64 {
+	return toFixed(num, 3)
+}
diff --git a/pkg/server/game_test.go b/pkg/server/game_test.go
new file mode 100644
index 0000000..bd1a51d
--- /dev/null
+++ b/pkg/server/game_test.go
@@ -0,0 +1,105 @@
+package server_test
+
+import (
+	"testing"
+
+	"github.com/iliadenisov/galaxy/pkg/server"
+)
+
+func Test_ShipType(t *testing.T) {
+	Gunship := server.ShipType{
+		Drive:    4,
+		Armament: 2,
+		Weapons:  2,
+		Shields:  4,
+		Cargo:    0,
+	}
+
+	if Gunship.EmptyMass() != 11. {
+		t.Errorf("Cruiser mass expected %.3f but %.3f given", 11., Gunship.EmptyMass())
+	}
+
+	Cruiser := server.ShipType{
+		Drive:    15,
+		Armament: 1,
+		Weapons:  15,
+		Shields:  15,
+		Cargo:    0,
+	}
+
+	if Cruiser.EmptyMass() != 45. {
+		t.Errorf("Cruiser mass expected %.3f but %.3f given", 45., Cruiser.EmptyMass())
+	}
+
+	sg := server.ShipGroup{
+		Type:    Cruiser,
+		Number:  1,
+		State:   "In_Orbit",
+		Drive:   1.0,
+		Weapons: 1.0,
+		Shields: 1.0,
+		Cargo:   1.0,
+	}
+
+	upgradeCost := sg.UpgradeDriveCost(2.0) +
+		sg.UpgradeWeaponsCost(2.0) +
+		sg.UpgradeShieldsCost(2.0) +
+		sg.UpgradeCargoCost(2.0)
+
+	if upgradeCost != 225. {
+		t.Errorf("Cruiser upgrade cost expected %.3f but %.3f given", 225., upgradeCost)
+	}
+}
+
+func Test_CargoCapacity(t *testing.T) {
+	test := func(cargoSize float64, expectCapacity float64) {
+		ship := server.ShipType{
+			Drive:    1,
+			Armament: 1,
+			Weapons:  1,
+			Shields:  1,
+			Cargo:    cargoSize,
+		}
+		sg := server.ShipGroup{
+			Type:    ship,
+			Number:  1,
+			State:   "In_Orbit",
+			Drive:   1.0,
+			Weapons: 1.0,
+			Shields: 1.0,
+			Cargo:   1.0,
+		}
+		if sg.CargoCapacity() != expectCapacity {
+			t.Errorf("expected CargoCapacity=%.3f but %.3f given", expectCapacity, sg.CargoCapacity())
+		}
+	}
+	test(1, 1.05)
+	test(5, 6.25)
+	test(10, 15)
+	test(50, 175)
+	test(100, 600)
+}
+
+func Test_BombingPower(t *testing.T) {
+	Gunship := server.ShipType{
+		Drive:    60.0,
+		Armament: 3,
+		Weapons:  30.0,
+		Shields:  100.0,
+		Cargo:    0.0,
+	}
+	sg := server.ShipGroup{
+		Type:    Gunship,
+		Number:  1,
+		State:   "In_Orbit",
+		Drive:   1.0,
+		Weapons: 1.0,
+		Shields: 1.0,
+		Cargo:   1.0,
+	}
+	expectedBombingPower := 139.295
+	result := sg.BombingPower()
+	if result != expectedBombingPower {
+		t.Errorf("expected BombingPower=%.3f but %.3f given", expectedBombingPower, result)
+	}
+}
diff --git a/pkg/storage/storage.go b/pkg/storage/storage.go
new file mode 100644
index 0000000..7cd6055
--- /dev/null
+++ b/pkg/storage/storage.go
@@ -0,0 +1,26 @@
+package storage
+
+import "github.com/iliadenisov/galaxy/pkg/server"
+
+// games/
+//       data.json - id, name, turn, schedule, status
+//       game123/
+//               racelist/<race_id>/data.json - account_id, name, status, war/peace(?), last_order, etc.
+//               order/<turn>/<race_id>/0.json - incoming orders
+//               turn/12/log/ - ?
+//               turn/12/order/<race_id>/0.json - processed orders
+//               turn/12/state/0.json - initital, contains <battle_numbers> for planet
+//                       state/<1...N>.json - instant commands changes state
+//               turn/12/report/global.json
+//                       report/<race_id>.json
+//               turn/12/battle/<planet_id>/<battle_number>.json
+
+type Storage interface {
+	ListGames() ([]server.GameIdentifier, error)
+
+	LoadRace(game_id server.GameIdentifier, race_id server.RaceIdentifier) (server.Race, error)
+	SaveRace(game_id server.GameIdentifier, race server.Race) error
+
+	LoadState(game_id server.GameIdentifier) (server.Game, error)
+	SaveState(game server.Game) error
+}