You are trapped in a room of zombies. Don't let them kill you, and prevent innocent people from being killed too! Buy upgrades and skills to strengthen your character. At the end of every wave, there will be health and energy drops.
Hold space to shoot. Up and Down keys move your character front and back, while Right and Left keys rotate your character. The Ctrl key turns the character around. To pause, press P, while another Q quits the game.