Your goal is to stay alive as long as possible while driving down an endless highway littered with broken cars and other debris. Zombies will jump onto your car and try to pull it over. To get rid of them, you can either shoot them (which consumes ammo) or run them into debris. The latter one is more effective, but needs careful steering since you mustn't bump directly into debris or your car will stop. Additionally, controlling the car gets more and more difficult if there are more zombies attached to it.
The car is controlled by tilting the device, whereas shooting is done by tapping the screen. Players may choose which weapons and car to use in a level. Weapons range from simple (pistol) to devastating (flame-thrower) and have different characteristics like reload speed or maximum ammo. New cars, weapons and levels get unlocked by reaching certain stats, like killing a set amount of zombies or driving at least a certain number of miles in a level etc. There is also a free version (Zombie Highway Lite), where only a subset of all unlockable items and levels is available.