===================================================================
--- original.js
+++ change.js
@@ -56,8 +56,27 @@
 			self.destroy();
 		}
 	};
 });
+// Block class
+var Block = Container.expand(function () {
+	var self = Container.call(this);
+	var blockGraphics = self.createAsset('block', 'Harmful block', 0.5, 1);
+	blockGraphics.scale.set(0.8);
+	self.speed = Obstacle.baseSpeed;
+	self.move = function () {
+		self.x -= self.speed;
+		if (self.x < -blockGraphics.width) {
+			self.destroy();
+		}
+	};
+	self.isHarmful = function () {
+		// Check if the player's bottom is above the top of the block, which means the player is jumping on it
+		var playerBottom = player.y + player.height;
+		var blockTop = self.y - blockGraphics.height / 2;
+		return playerBottom < blockTop;
+	};
+});
 
 /**** 
 * Initialize Game
 ****/
@@ -83,20 +102,21 @@
 	player.update();
 	// Move each obstacle and check for collisions
 	for (var i = obstacles.length - 1; i >= 0; i--) {
 		obstacles[i].move();
-		if (player.intersects(obstacles[i])) {
+		if (player.intersects(obstacles[i]) && !(obstacles[i] instanceof Block && !obstacles[i].isHarmful())) {
 			LK.effects.flashScreen(0xff0000, 500);
 			LK.showGameOver();
 		}
 	}
 	// Increase obstacle speed every 25 seconds and make it 10 times faster
 	if (LK.ticks % 1500 === 0) {
 		Obstacle.baseSpeed = 3;
 	}
-	// Spawn obstacles
+	// Spawn obstacles and blocks
 	if (LK.ticks % 180 === 0) {
-		var obstacle = new Obstacle();
+		var obstacleType = Math.random() < 0.5 ? Obstacle : Block;
+		var obstacle = new obstacleType();
 		obstacle.x = game.width;
 		obstacle.y = game.height - 100;
 		obstacles.push(obstacle);
 		game.addChild(obstacle);