Conscientious Objector (2008)

Conscientious Objector is a Doom 3 mod that uses the first three levels of the commercial game, stripped bare and repopulated, together with some custom code that stops the player from being able to kill anything. Sure, you can shoot the zombies all you like, and they will fall down.. it's just that they'll get back up again... On top of this, rather than being told you're great, like most FPS games, you've got an aggressive NPC on your case and in your ear, who'd like nothing better than to see you end up as a zombie's breakfast, and is going to let you know any chance he gets.

Storyline

In 2147, two years after the Mars Base fiasco, the Union Aerospace Corporation drove the Expendable Resource Reconnaissance Bill through World Government. Primarily, the bill was intended to avoid further waste of valuable resources when returning to the sealed off facility. The average space marine cost over two million dollars to train and equip - each lost marine represented a serious drain on UAC resources. The ERRB solved this problem by ensuring a steady supply of low cost resources for missions with high casualty rates from maximum security prisons. The most valuable assets came from the Glasshouse: marines who had refused to bear arms. These prisoners were highly trained, psychologically stable and displayed strong survival instincts. And, of course, if they never made it back, they wouldn't be missed. You're going back to Mars. But this time, your shotgun has only got rubber bullets in it. Conscientious Objector: killing is for wimps.