If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Mouse - Aim / Shoot.
Aliens have taken over the space station you're on and they are hell bent on hacking into its mainframe and retrieving important top secret information! As the soul surviving space trooper the fate of this vital information lies in your hands, it's your job to protect the data and stop the Aliens at all costs. Good luck!