diff --git a/examples/2048/2048/board.go b/examples/2048/2048/board.go
index 4bfbf1292..74b0685dd 100644
--- a/examples/2048/2048/board.go
+++ b/examples/2048/2048/board.go
@@ -45,16 +45,12 @@ func (b *Board) tileAt(x, y int) *Tile {
 	return tileAt(b.tiles, x, y)
 }
 
-func (b *Board) isAnimating() bool {
+func (b *Board) Update(input *Input) error {
 	for t := range b.tiles {
-		if t.isAnimating() {
-			return true
+		if err := t.Update(); err != nil {
+			return err
 		}
 	}
-	return false
-}
-
-func (b *Board) Update(input *Input) error {
 	if 0 < len(b.tasks) {
 		t := b.tasks[0]
 		err := t()
@@ -65,6 +61,11 @@ func (b *Board) Update(input *Input) error {
 		}
 		return nil
 	}
+	for t := range b.tiles {
+		if t.IsAnimating() {
+			return nil
+		}
+	}
 	if dir, ok := input.Dir(); ok {
 		if err := b.Move(dir); err != nil {
 			return err
@@ -79,12 +80,7 @@ func (b *Board) Move(dir Dir) error {
 	}
 	b.tasks = append(b.tasks, func() error {
 		for t := range b.tiles {
-			if err := t.Update(); err != nil {
-				return err
-			}
-		}
-		for t := range b.tiles {
-			if t.isAnimating() {
+			if t.IsAnimating() {
 				return nil
 			}
 		}
@@ -93,6 +89,9 @@ func (b *Board) Move(dir Dir) error {
 	b.tasks = append(b.tasks, func() error {
 		nextTiles := map[*Tile]struct{}{}
 		for t := range b.tiles {
+			if t.IsAnimating() {
+				panic("not reach")
+			}
 			if t.next.value != 0 {
 				panic("not reach")
 			}
@@ -137,7 +136,7 @@ func (b *Board) Draw(boardImage *ebiten.Image) error {
 	animatingTiles := map[*Tile]struct{}{}
 	nonAnimatingTiles := map[*Tile]struct{}{}
 	for t := range b.tiles {
-		if t.isAnimating() {
+		if t.IsAnimating() {
 			animatingTiles[t] = struct{}{}
 		} else {
 			nonAnimatingTiles[t] = struct{}{}
diff --git a/examples/2048/2048/tile.go b/examples/2048/2048/tile.go
index 94fa61ae6..90b3a72c0 100644
--- a/examples/2048/2048/tile.go
+++ b/examples/2048/2048/tile.go
@@ -63,7 +63,7 @@ func (t *Tile) NextPos() (int, int) {
 	return t.next.x, t.next.y
 }
 
-func (t *Tile) isAnimating() bool {
+func (t *Tile) IsAnimating() bool {
 	return 0 < t.animationCount
 }
 
@@ -121,7 +121,10 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
 			if t == nil {
 				continue
 			}
-			if t.animationCount != 0 {
+			if t.next != (TileData{}) {
+				panic("not reach")
+			}
+			if t.IsAnimating() {
 				panic("not reach")
 			}
 			ii := i
@@ -155,8 +158,8 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
 			next.value = t.current.value
 			if tt := nextTileAt(tiles, ii, jj); tt != t && tt != nil {
 				next.value = t.current.value + tt.next.value
-				tt.next = TileData{}
-				tt.animationCount = 1
+				tt.next.value = 0
+				tt.animationCount = maxAnimationCount
 			}
 			next.x = ii
 			next.y = jj
@@ -170,7 +173,7 @@ func MoveTiles(tiles map[*Tile]struct{}, size int, dir Dir) bool {
 func addRandomTile(tiles map[*Tile]struct{}, size int) error {
 	cells := make([]bool, size*size)
 	for t := range tiles {
-		if t.isAnimating() {
+		if t.IsAnimating() {
 			panic("not reach")
 		}
 		i := t.current.x + t.current.y*size
@@ -200,7 +203,7 @@ func addRandomTile(tiles map[*Tile]struct{}, size int) error {
 
 func (t *Tile) Update() error {
 	if t.animationCount == 0 {
-		if t.next.value != 0 {
+		if t.next != (TileData{}) {
 			panic("not reach")
 		}
 		return nil
@@ -264,7 +267,7 @@ func (t *Tile) Draw(boardImage *ebiten.Image) error {
 	y := j*tileSize + (j+1)*tileMargin
 	nx := ni*tileSize + (ni+1)*tileMargin
 	ny := nj*tileSize + (nj+1)*tileMargin
-	if 0 < t.animationCount && t.next.value != 0 {
+	if 0 < t.animationCount {
 		rate := float64(t.animationCount) / maxAnimationCount
 		x = mean(x, nx, rate)
 		y = mean(y, ny, rate)