If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Underdog City has been swamped with zombies. To contain the infection, the town has been closed up. You play Jack the unemployed Space Lumberjack, who didn't get the memo and is now the only survivor in town. His survival chances are close to none,but he's not going down without a fight!
WASD/Arrow keys - To move.
Mouse - To aim, left click to shoot.