If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Mouse - shoot.
A government experiment gone wrong or perhaps right depends on what you really think has seen 95% of the human race crumble into a mutant walking dead infestation on an apocalyptic scale. You and your men need to weapon up and take them out using a wide range of ammo and some pretty cool night time google wear. Good luck!