diff --git a/go.mod b/go.mod
index 20a0277..44fb9b9 100644
--- a/go.mod
+++ b/go.mod
@@ -8,7 +8,8 @@ require (
 	github.com/hajimehoshi/ebiten/v2 v2.4.16 // indirect
 	github.com/hajimehoshi/file2byteslice v1.0.0 // indirect
 	github.com/jezek/xgb v1.1.0 // indirect
-	golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56 // indirect
+	github.com/surdeus/godat v0.0.0-20230217130825-eddf2c345cb7 // indirect
+	golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb // indirect
 	golang.org/x/exp/shiny v0.0.0-20230213192124-5e25df0256eb // indirect
 	golang.org/x/image v0.5.0 // indirect
 	golang.org/x/mobile v0.0.0-20221110043201-43a038452099 // indirect
diff --git a/go.sum b/go.sum
index efe0900..7bb5a51 100644
--- a/go.sum
+++ b/go.sum
@@ -21,6 +21,8 @@ github.com/jezek/xgb v1.1.0/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFl
 github.com/jfreymuth/oggvorbis v1.0.4/go.mod h1:1U4pqWmghcoVsCJJ4fRBKv9peUJMBHixthRlBeD6uII=
 github.com/jfreymuth/vorbis v1.0.2/go.mod h1:DoftRo4AznKnShRl1GxiTFCseHr4zR9BN3TWXyuzrqQ=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
+github.com/surdeus/godat v0.0.0-20230217130825-eddf2c345cb7 h1:Fmoxhb42mS6BEmLF2spRiYlzes+S1VrEw0PnbR1ktUM=
+github.com/surdeus/godat v0.0.0-20230217130825-eddf2c345cb7/go.mod h1:tQGz8oe6Qig5yjYobaW1O8paXGGhzdukg8nT2bpvfes=
 github.com/yuin/goldmark v1.4.0/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
@@ -30,6 +32,8 @@ golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5y
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56 h1:estk1glOnSVeJ9tdEZZc5mAMDZk5lNJNyJ6DvrBkTEU=
 golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
+golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb h1:PaBZQdo+iSDyHT053FjUCgZQ/9uqVwPOcl7KSWhKn6w=
+golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
 golang.org/x/exp/shiny v0.0.0-20230213192124-5e25df0256eb h1:gdeQX7xJSkTNF+Sw7++XNIOo4pGL0CjQv3N2Vm1Erxk=
 golang.org/x/exp/shiny v0.0.0-20230213192124-5e25df0256eb/go.mod h1:UH99kUObWAZkDnWqppdQe5ZhPYESUw8I0zVV1uWBR+0=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
diff --git a/src/cmd/test/main.go b/src/cmd/test/main.go
index 3263c8e..121927b 100644
--- a/src/cmd/test/main.go
+++ b/src/cmd/test/main.go
@@ -4,6 +4,10 @@ import (
 	"github.com/surdeus/gox/src/gx"
 )
 
+type Player struct {
+	gx.Object
+}
+
 func main() {
 	e := gx.New(&gx.WindowConfig{
 		Title: "Test title",
@@ -11,5 +15,6 @@ func main() {
 		Height: 320,
 	})
 
+	e.Add(0, Player{})
 	e.Run()
 }
diff --git a/src/gx/main.go b/src/gx/main.go
index 408ebb3..836c7e0 100644
--- a/src/gx/main.go
+++ b/src/gx/main.go
@@ -2,8 +2,13 @@ package gx
 
 import (
 	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/surdeus/godat/src/sparsex"
+	"fmt"
 )
 
+// The type represents order of drawing.
+type Layer int
+
 type WindowConfig struct {
 	Title string
 	Width, Height int
@@ -11,6 +16,8 @@ type WindowConfig struct {
 
 type Engine struct {
 	wcfg *WindowConfig
+	layers *sparsex.Sparse[Layer, *[]Behaver]
+	behavers []Behaver
 }
 
 type engine Engine
@@ -20,13 +27,39 @@ func New(
 ) *Engine {
 	return &Engine{
 		wcfg: cfg,
+		layers: sparsex.New[
+			Layer,
+			*[]Behaver,
+		](true),
 	}
 }
 
+func (e *Engine) Add(l Layer, b Behaver) {
+	g, ok := e.layers.Get(l)
+	if !ok {
+		e.layers.Set(
+			l,
+			&[]Behaver{b},
+		)
+	} else {
+		set := append(*g, b)
+		*g = set
+	}
+
+	e.behavers = append(e.behavers, b)
+}
+
 func (e *engine) Update() error {
+	eng := (*Engine)(e)
+	for _, v := range eng.behavers {
+		v.Update(eng)
+		fmt.Println(v)
+	}
+
 	return nil
 }
 
+
 func (e *engine) Draw(s *ebiten.Image) {
 }
 
diff --git a/src/gx/object.go b/src/gx/object.go
index 4344ba8..ab07de3 100644
--- a/src/gx/object.go
+++ b/src/gx/object.go
@@ -1,11 +1,16 @@
 package gx
 
 type Behaver interface {
-	Start()
-	Update()
+	Start(*Engine)
+	Update(*Engine)
 	GetObject() *Object
 }
 
+// The object that is drawn by sprite
+/// based on the transform.
+type Sprite struct {
+}
+
 // The object type represents
 // basic information for interaction
 // with the engine.
@@ -13,9 +18,10 @@ type Object struct {
 	T Transform
 }
 
-func (o *Object) Start() {}
-func (o *Object) Update() {}
-func (o *Object) GetObject() *Object {
-	return o
+// The functions that 
+func (o Object) Start(e *Engine) {}
+func (o Object) Update(e *Engine) {}
+func (o Object) GetObject() *Object {
+	return &o
 }