If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
It seems like it was over... You escaped from the dark factory but zombies are everywhere around you. The helicopter will come to your rescue. Defend your campfire, repair your barricades, aim and shoot them. It's up to you to survive for 20 minutes!
W,A,S,D - To move Mouse key - To aim and shoot.
R - To reload weapon,E - To switch devices. Space bar - To open inventory. 1 - To switch Guns,2 - To switch RIfles,3 - To switch Launchers.