diff --git a/src/game/mouse/space_invaders/alien.js b/src/game/mouse/space_invaders/alien.js
index bf65f96..d9cf7cb 100644
--- a/src/game/mouse/space_invaders/alien.js
+++ b/src/game/mouse/space_invaders/alien.js
@@ -1,155 +1,155 @@
-class Alien extends Phaser.Sprite {
+Alien.prototype = Object.create(Phaser.Sprite.prototype);
+Alien.constructor = Alien;
 
-	constructor(initialX, initialY, onGoOnstageFunction, onFiredFunction, onEscapedFunction) {
-		super();
+function Alien(initialX, initialY, onGoOnstageFunction, onFiredFunction, onEscapedFunction) {
+	// super();
 
-		this.isActivated = false;
-		this.isOnWaitingRoom = true;
-		this.speedGrowing = Alien.DEFAULT_SPEED_SEC;
+	this.isActivated = false;
+	this.isOnWaitingRoom = true;
+	this.speedGrowing = Alien.DEFAULT_SPEED_SEC;
 
-		this.initialX = initialX;
-		this.initialY = initialY;
+	this.initialX = initialX;
+	this.initialY = initialY;
 
-		this.tweenScaleUp = null;
-		this.tweenScaleDown = null;
+	this.tweenScaleUp = null;
+	this.tweenScaleDown = null;
 
-		this.onGoOnstageFunction = onGoOnstageFunction;
-		this.onFiredFunction = onFiredFunction;
-		this.onEscapedFunction = onEscapedFunction;
+	this.onGoOnstageFunction = onGoOnstageFunction;
+	this.onFiredFunction = onFiredFunction;
+	this.onEscapedFunction = onEscapedFunction;
 
-		Phaser.Sprite.call(this, game, this.initialX, this.initialY, 'alien_normal');
-		this.anchor.set(0.5);
-		this.goWaitingRoom();
+	Phaser.Sprite.call(this, game, this.initialX, this.initialY, 'alien_normal');
+	this.anchor.set(0.5);
+	this.goWaitingRoom();
 
 
-		this.inputEnabled = true;
-		this.events.onInputOut.add(this.onOut, this);
-		this.events.onInputOver.add(this.onOver, this);
-		this.events.onInputDown.add(this.onDown, this);
-
-		game.add.existing(this);
-	}
-
-	onOut() {
-		if(!this.isActivated)
-			return;
-
-		this.tint = 0xffffff;
-	}
-
-	onOver() {
-		if(!this.isActivated)
-			return;
-
-		this.tint = 0xffaaaa;
-	}
-
-	onDown() {
-		if(!this.isActivated)
-			return;
-
-		if(this.isOnWaitingRoom) {
-			this.goOnstage();
-			return;
-		} else {
-			this.onFired();
-		}
-	}
-
-
-	stop() {
-		this.setActive(false);
-		this.removeTween();
-
-		// if(this.isOnWaitingRoom !== true)
-		// 	this.scale.set(0);
-	}
-
-	setActive(isActivated) {
-		this.isActivated = isActivated;
-
-		if(this.isActivated) {
-			this.tint = 0xffffff;
-		} else {
-			this.tint = 0x555555;
-		}
-	}
-
-	removeTween() {
-		if(this.tweenScaleUp !== null) {
-			this.tweenScaleUp.stop();
-			this.tweenScaleUp = null;
-		}
-		if(this.tweenScaleDown !== null) {
-			this.tweenScaleDown.stop();
-			this.tweenScaleDown = null;
-		}
-	}
-
-	goWaitingRoom() {
-		this.isOnWaitingRoom = true;
-
-		this.x = this.initialX;
-		this.y = this.initialY;
-		this.scale.set(Alien.WAITING_SCALE);
-	}
-
-	goOnstage() {
-		this.isOnWaitingRoom = false;
-		this.goRandomPosition();
-
-		if(typeof this.onGoOnstageFunction !== "undefined")
-			this.onGoOnstageFunction();
-	}
-
-	onFired() {
-		if(typeof this.onFiredFunction !== "undefined")
-			this.onFiredFunction(this);
-
-		this.goRandomPosition();
-	}
-
-	goRandomPosition() {
-		// set random position
-		const SPAWN_BOX_LEFT		= 80;
-		const SPAWN_BOX_WIDTH		= game.world.width - 160;
-		const SPAWN_BOX_TOP		= 280;
-		const SPAWN_BOX_HEIGHT	= game.world.height - 400;
-
-		this.x = SPAWN_BOX_LEFT + Math.random() * SPAWN_BOX_WIDTH;
-		this.y = SPAWN_BOX_TOP + Math.random() * SPAWN_BOX_HEIGHT;
-
-		// if(isDebugMode()) {
-		// 	this.game.add.graphics()
-		// 		.beginFill(0xffffff, 0.1)
-		// 		.drawRect(SPAWN_BOX_LEFT, SPAWN_BOX_TOP, SPAWN_BOX_WIDTH, SPAWN_BOX_HEIGHT);
-		// }
-
-		this.tint = 0xffffff;
-		this.scale.set(Alien.ONSTAGE_MIN_SCALE);
-
-		// start scale tween animation
-		this.removeTween();
-
-		this.tweenScaleUp = game.add.tween(this.scale)
-			.to( { x: Alien.ONSTAGE_MAX_SCALE, y: Alien.ONSTAGE_MAX_SCALE }, Alien.DEFAULT_SPEED_SEC, Phaser.Easing.Linear.None, false);
-		this.tweenScaleDown = game.add.tween(this.scale)
-			.to( { x: 0, y: 0 }, Alien.DEFAULT_SPEED_SEC, Phaser.Easing.Linear.None, false);
-		this.tweenScaleUp.chain(this.tweenScaleDown);
-		this.tweenScaleDown.onComplete.addOnce(this.onEscaped, this);
-		this.tweenScaleUp.start();
-	}
-
-	onEscaped() {
-		if(!this.isActivated)
-			return;
-
-		if(typeof this.onEscapedFunction !== "undefined")
-			this.onEscapedFunction();
-	}
+	this.inputEnabled = true;
+	this.events.onInputOut.add(this.onOut, this);
+	this.events.onInputOver.add(this.onOver, this);
+	this.events.onInputDown.add(this.onDown, this);
 
+	game.add.existing(this);
 }
 
+Alien.prototype.onOut = function() {
+	if(!this.isActivated)
+		return;
+
+	this.tint = 0xffffff;
+}
+
+Alien.prototype.onOver = function() {
+	if(!this.isActivated)
+		return;
+
+	this.tint = 0xffaaaa;
+}
+
+Alien.prototype.onDown = function() {
+	if(!this.isActivated)
+		return;
+
+	if(this.isOnWaitingRoom) {
+		this.goOnstage();
+		return;
+	} else {
+		this.onFired();
+	}
+}
+
+
+Alien.prototype.stop = function() {
+	this.setActive(false);
+	this.removeTween();
+
+	// if(this.isOnWaitingRoom !== true)
+	// 	this.scale.set(0);
+}
+
+Alien.prototype.setActive = function(isActivated) {
+	this.isActivated = isActivated;
+
+	if(this.isActivated) {
+		this.tint = 0xffffff;
+	} else {
+		this.tint = 0x555555;
+	}
+}
+
+Alien.prototype.removeTween = function() {
+	if(this.tweenScaleUp !== null) {
+		this.tweenScaleUp.stop();
+		this.tweenScaleUp = null;
+	}
+	if(this.tweenScaleDown !== null) {
+		this.tweenScaleDown.stop();
+		this.tweenScaleDown = null;
+	}
+}
+
+Alien.prototype.goWaitingRoom = function() {
+	this.isOnWaitingRoom = true;
+
+	this.x = this.initialX;
+	this.y = this.initialY;
+	this.scale.set(Alien.WAITING_SCALE);
+}
+
+Alien.prototype.goOnstage = function() {
+	this.isOnWaitingRoom = false;
+	this.goRandomPosition();
+
+	if(typeof this.onGoOnstageFunction !== "undefined")
+		this.onGoOnstageFunction();
+}
+
+Alien.prototype.onFired = function() {
+	if(typeof this.onFiredFunction !== "undefined")
+		this.onFiredFunction(this);
+
+	this.goRandomPosition();
+}
+
+Alien.prototype.goRandomPosition = function() {
+	// set random position
+	const SPAWN_BOX_LEFT		= 80;
+	const SPAWN_BOX_WIDTH		= game.world.width - 160;
+	const SPAWN_BOX_TOP		= 280;
+	const SPAWN_BOX_HEIGHT	= game.world.height - 400;
+
+	this.x = SPAWN_BOX_LEFT + Math.random() * SPAWN_BOX_WIDTH;
+	this.y = SPAWN_BOX_TOP + Math.random() * SPAWN_BOX_HEIGHT;
+
+	// if(isDebugMode()) {
+	// 	this.game.add.graphics()
+	// 		.beginFill(0xffffff, 0.1)
+	// 		.drawRect(SPAWN_BOX_LEFT, SPAWN_BOX_TOP, SPAWN_BOX_WIDTH, SPAWN_BOX_HEIGHT);
+	// }
+
+	this.tint = 0xffffff;
+	this.scale.set(Alien.ONSTAGE_MIN_SCALE);
+
+	// start scale tween animation
+	this.removeTween();
+
+	this.tweenScaleUp = game.add.tween(this.scale)
+		.to( { x: Alien.ONSTAGE_MAX_SCALE, y: Alien.ONSTAGE_MAX_SCALE }, Alien.DEFAULT_SPEED_SEC, Phaser.Easing.Linear.None, false);
+	this.tweenScaleDown = game.add.tween(this.scale)
+		.to( { x: 0, y: 0 }, Alien.DEFAULT_SPEED_SEC, Phaser.Easing.Linear.None, false);
+	this.tweenScaleUp.chain(this.tweenScaleDown);
+	this.tweenScaleDown.onComplete.addOnce(this.onEscaped, this);
+	this.tweenScaleUp.start();
+}
+
+Alien.prototype.onEscaped = function() {
+	if(!this.isActivated)
+		return;
+
+	if(typeof this.onEscapedFunction !== "undefined")
+		this.onEscapedFunction();
+}
+
+
 Alien.DEFAULT_SPEED_SEC		= 3000;
 Alien.WAITING_SCALE			= 2;
 Alien.ONSTAGE_MIN_SCALE		= 0.1;
diff --git a/src/game/mouse/space_invaders/alien_timer.js b/src/game/mouse/space_invaders/alien_timer.js
index a7a3347..3ab134f 100644
--- a/src/game/mouse/space_invaders/alien_timer.js
+++ b/src/game/mouse/space_invaders/alien_timer.js
@@ -1,93 +1,90 @@
-class AlienTimer {
+function AlienTimer(aliens) {
+	this.aliens = aliens;
+	this.activatedAlienIndex = 0;
 
-	constructor(aliens) {
-		this.aliens = aliens;
-		this.activatedAlienIndex = 0;
+	var posX = this.aliens[0].x;
+	var posY = this.aliens[0].y - AlienTimer.MOVE_UP_AMOUNT_PX;
+	this.timerText = game.add.text(posX, posY, "30", AlienTimer.DEFAULT_TEXT_FONT);
+	this.timerText.anchor.set(0.5);
 
-		let posX = this.aliens[0].x;
-		let posY = this.aliens[0].y - AlienTimer.MOVE_UP_AMOUNT_PX;
-		this.timerText = game.add.text(posX, posY, "30", AlienTimer.DEFAULT_TEXT_FONT);
-		this.timerText.anchor.set(0.5);
-
-		var grd = this.timerText.context.createLinearGradient(0, 0, 0, this.timerText.height);
-		grd.addColorStop(0, '#FFD68E');
-		grd.addColorStop(1, '#B34C00');
-		this.timerText.fill = grd;
-		// this.setShadow(3, 3, 'rgba(0, 0, 0, 0.5)', 2);
-		this.timerText.stroke = '#000';
-		this.timerText.strokeThickness = 5;
-
-		this.timerEvent = null;
-		this.timeInterval = AlienTimer.DEFAULT_TIME_GAP_SEC;
-		this.timeLeft = this.timeInterval;
-	}
-
-	start() {
-		this.enableTimerOn(this.getActivatedAlien());
-		// this.getActivatedAlien().setActive(true);
-		this.timerText.text = this.timeLeft.toString();
-		if(this.timerEvent === null)
-			this.timerEvent = game.time.events.loop(Phaser.Timer.SECOND, this.updateTimer, this);
-	}
-
-	pause() {
-	}
-
-	stop() {
-		if(this.timerEvent)
-			this.removeTimer();
-		this.timerText.text = "";
-
-		for(let i = 0; i < this.aliens.length; i++)
-			this.aliens[i].stop();
-	}
-
-	next() {
-		this.timeLeft = this.timeInterval;
-		this.timerText.text = this.timeLeft.toString();
-
-		this.activatedAlienIndex++;
-		if(this.activatedAlienIndex >= this.aliens.length) {
-			this.timerText.text = "";
-			this.removeTimer();
-			return null;
-		}
-
-		this.enableTimerOn(this.getActivatedAlien());
-	}
-
-	getActivatedAlien() {
-		return this.aliens[this.activatedAlienIndex];
-	}
-
-	enableTimerOn(alien) {
-		alien.setActive(true);
-		this.timerText.x = alien.x;
-	}
-
-	disableTimerOn(alien) {
-		alien.setActive(false);
-		this.timerText.text = "";
-	}
-
-	updateTimer() {
-		this.timeLeft--;
-		if(this.timeLeft == 0) {
-			this.timeLeft = this.timeInterval;
-
-			this.getActivatedAlien().goOnstage();
-		} else {
-			this.timerText.text = this.timeLeft.toString();
-		}
-	}
-
-	removeTimer() {
-		game.time.events.remove(this.timerEvent);
-		this.timerEvent = null;
-	}
+	var grd = this.timerText.context.createLinearGradient(0, 0, 0, this.timerText.height);
+	grd.addColorStop(0, '#FFD68E');
+	grd.addColorStop(1, '#B34C00');
+	this.timerText.fill = grd;
+	// this.setShadow(3, 3, 'rgba(0, 0, 0, 0.5)', 2);
+	this.timerText.stroke = '#000';
+	this.timerText.strokeThickness = 5;
 
+	this.timerEvent = null;
+	this.timeInterval = AlienTimer.DEFAULT_TIME_GAP_SEC;
+	this.timeLeft = this.timeInterval;
 }
 
+AlienTimer.prototype.start = function() {
+	this.enableTimerOn(this.getActivatedAlien());
+	// this.getActivatedAlien().setActive(true);
+	this.timerText.text = this.timeLeft.toString();
+	if(this.timerEvent === null)
+		this.timerEvent = game.time.events.loop(Phaser.Timer.SECOND, this.updateTimer, this);
+}
+
+AlienTimer.prototype.pause = function() {
+}
+
+AlienTimer.prototype.stop = function() {
+	if(this.timerEvent)
+		this.removeTimer();
+	this.timerText.text = "";
+
+	for(var i = 0; i < this.aliens.length; i++)
+		this.aliens[i].stop();
+}
+
+AlienTimer.prototype.next = function() {
+	this.timeLeft = this.timeInterval;
+	this.timerText.text = this.timeLeft.toString();
+
+	this.activatedAlienIndex++;
+	if(this.activatedAlienIndex >= this.aliens.length) {
+		this.timerText.text = "";
+		this.removeTimer();
+		return null;
+	}
+
+	this.enableTimerOn(this.getActivatedAlien());
+}
+
+AlienTimer.prototype.getActivatedAlien = function() {
+	return this.aliens[this.activatedAlienIndex];
+}
+
+AlienTimer.prototype.enableTimerOn = function(alien) {
+	alien.setActive(true);
+	this.timerText.x = alien.x;
+}
+
+AlienTimer.prototype.disableTimerOn = function(alien) {
+	alien.setActive(false);
+	this.timerText.text = "";
+}
+
+AlienTimer.prototype.updateTimer = function() {
+	this.timeLeft--;
+	if(this.timeLeft == 0) {
+		this.timeLeft = this.timeInterval;
+
+		this.getActivatedAlien().goOnstage();
+	} else {
+		this.timerText.text = this.timeLeft.toString();
+	}
+}
+
+AlienTimer.prototype.removeTimer = function() {
+	game.time.events.remove(this.timerEvent);
+	this.timerEvent = null;
+}
+
+
 AlienTimer.DEFAULT_TEXT_FONT		= {
 	font: "bold 30px Arial",
 	boundsAlignH: "center",		// left, center. right
diff --git a/src/game/mouse/space_invaders/loading.js b/src/game/mouse/space_invaders/loading.js
index d107424..52e4e0f 100644
--- a/src/game/mouse/space_invaders/loading.js
+++ b/src/game/mouse/space_invaders/loading.js
@@ -1,16 +1,10 @@
-/////////////////////////////
-// Loading
+var Loading = {
 
-// var x = 32;
-// var y = 80;
-
-class Loading {
-
-	preload() {
+	preload: function() {
 		// this.game.load.image('loadingbar', './image/phaser.png');
-	}
+	},
 
-	create() {
+	create: function() {
 		// let userID = sessionStorage.getItem("UserID");
 		// console.log("userID : " + userID);
 
@@ -30,9 +24,9 @@ class Loading {
 		this.game.load.onLoadComplete.add(this.loadComplete, this);
 
 		this.startLoading();
-	}
+	},
 
-	startLoading() {
+	startLoading: function() {
 		this.game.load.image('icon_fullscreen',	'../../../resources/image/icon/fullscreen_white.png');
 
 		this.game.load.image('star',	'../../../resources/image/background/star_7x7.png');
@@ -64,9 +58,9 @@ class Loading {
 		// this.game.load.image('medal_bronze', './image/medal_bronze.png');
 
 		this.game.load.start();
-	}
+	},
 
-	fileComplete(progress, cacheKey, success, totalLoaded, totalFiles) {
+	fileComplete: function(progress, cacheKey, success, totalLoaded, totalFiles) {
 		// this.preloadBar.alpha = progress / 100;
 
 		// console.log('progress : ' + progress);
@@ -82,9 +76,9 @@ class Loading {
 		// 	x = 32;
 		// 	y += 332;
 		// }
-	}
+	},
 
-	loadComplete(progress, cacheKey, success, totalLoaded, totalFiles) {
+	loadComplete: function(progress, cacheKey, success, totalLoaded, totalFiles) {
 		// this.preloadBar.alpha = 1;
 
 		if(isDebugMode()) {