diff --git a/.gitignore b/.gitignore
index 77e14fe..fe5c6de 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ bak
 dump*
 rect*
 *profile
+*prof
diff --git a/config.go b/config.go
index 1d1d156..724d104 100644
--- a/config.go
+++ b/config.go
@@ -267,3 +267,7 @@ func (config *Config) ToggleGridlines() {
 	config.ShowGrid = !config.ShowGrid
 	config.RestartCache = true
 }
+
+func (config *Config) ToggleEvolution() {
+	config.ShowEvolution = !config.ShowEvolution
+}
diff --git a/game.go b/game.go
index 9f73464..a7313f4 100644
--- a/game.go
+++ b/game.go
@@ -49,7 +49,10 @@ func (game *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
 
 func (game *Game) Update() error {
 	scene := game.GetCurrentScene()
-	scene.Update()
+
+	if quit := scene.Update(); quit != nil {
+		return quit
+	}
 
 	next := scene.GetNext()
 	if next != game.CurrentScene {
diff --git a/options.go b/options.go
index 0c883fe..c8a04fd 100644
--- a/options.go
+++ b/options.go
@@ -95,7 +95,7 @@ func (scene *SceneOptions) Init() {
 
 	invert := NewCheckbox("Invert",
 		func(args *widget.CheckboxChangedEventArgs) {
-			scene.Config.Invert = true
+			scene.Config.ToggleInvert()
 		})
 	scene.SetInitialValue(invert, scene.Config.Invert)
 
@@ -105,6 +105,12 @@ func (scene *SceneOptions) Init() {
 		})
 	scene.SetInitialValue(gridlines, scene.Config.ShowGrid)
 
+	evolution := NewCheckbox("Show evolution traces",
+		func(args *widget.CheckboxChangedEventArgs) {
+			scene.Config.ToggleEvolution()
+		})
+	scene.SetInitialValue(evolution, scene.Config.ShowEvolution)
+
 	separator := NewSeparator(3)
 
 	cancel := NewMenuButton("Close",
@@ -116,6 +122,7 @@ func (scene *SceneOptions) Init() {
 	rowContainer.AddChild(debugging)
 	rowContainer.AddChild(invert)
 	rowContainer.AddChild(gridlines)
+	rowContainer.AddChild(evolution)
 	rowContainer.AddChild(separator)
 	rowContainer.AddChild(cancel)
 
diff --git a/play.go b/play.go
index 2c974f3..2bea6d4 100644
--- a/play.go
+++ b/play.go
@@ -5,7 +5,6 @@ import (
 	"image"
 	"image/color"
 	"log"
-	"os"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
@@ -162,11 +161,15 @@ func (scene *ScenePlay) Reset() {
 }
 
 // check user input
-func (scene *ScenePlay) CheckInput() {
+func (scene *ScenePlay) CheckExit() error {
 	if inpututil.IsKeyJustPressed(ebiten.KeyQ) {
-		os.Exit(0)
+		return ebiten.Termination
 	}
 
+	return nil
+}
+
+func (scene *ScenePlay) CheckInput() {
 	if inpututil.IsKeyJustPressed(ebiten.KeyEscape) {
 		scene.SetNext(Menu)
 	}
@@ -176,7 +179,6 @@ func (scene *ScenePlay) CheckInput() {
 	}
 
 	if inpututil.IsKeyJustPressed(ebiten.KeyC) {
-		fmt.Println("mark mode on")
 		scene.Config.Markmode = true
 		scene.Config.Paused = true
 	}
@@ -297,6 +299,10 @@ func (scene *ScenePlay) CheckMarkInput() {
 		return
 	}
 
+	if inpututil.IsKeyJustPressed(ebiten.KeyEscape) {
+		scene.Config.Markmode = false
+	}
+
 	if ebiten.IsMouseButtonPressed(ebiten.MouseButton0) {
 		if !scene.MarkTaken {
 			scene.Mark = scene.GetWorldCursorPos()
@@ -391,6 +397,10 @@ func (scene *ScenePlay) Update() error {
 		return nil
 	}
 
+	if quit := scene.CheckExit(); quit != nil {
+		return quit
+	}
+
 	scene.CheckInput()
 	scene.CheckDraggingInput()
 	scene.CheckMarkInput()
@@ -498,6 +508,10 @@ func (scene *ScenePlay) DrawDebug(screen *ebiten.Image) {
 			paused = "-- paused --"
 		}
 
+		if scene.Config.Markmode {
+			paused = "-- mark --"
+		}
+
 		x, y := ebiten.CursorPosition()
 		debug := fmt.Sprintf(
 			DEBUG_FORMAT,