If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Zombie Carpocalypse is another great unity game where this time you can prepare for a proper disaster. The city was hit by a group of zombie creatures that terrorize the population. Therefore, you must take it into your own hands and destroy as many of them as possible. With that will help your car and also some weapons that you can buy.