Timmy has to survive as many waves of zombies as he can without getting hit 3 times. He uses the arrow keys to move and the space bar to fire his gun. To get on to the next wave he must kill the lead zombie (controlled by someone else by using wasd). The other zombies don't matter, they're just there to help the lead zombie kill Timmy. If there is no one able to control the lead zombie, click the 1 player mode button at the start of the first wave. As Timmy clears more waves, there are more zombies. The zombies also get faster and stronger, so watch out! (On 1 player mode, the lead zombie doesn't appear until after a set time based on the wave you are on)