You are the leader of a group of survivors, and you have to cross the infected city, where zombies outnumbered the humans! Try to reach the safe area as you run your trolley and shoot all zombies! Don't forget to collect the coins with your mouse, you'll need to buy new abilities and guns to complete your mission.
Use your mouse to aim and shoot, R to reload your weapon, G to throw grenade (once bought). Press Space bar to jump.