Kill Theory (2009)

A group of college students visit a secluded vacation home to celebrate their upcoming graduation. The fun doesn't last long when a sadistic psychopath forces them to participate in his deadly contest. The rules are simple -- in order to survive they must kill each other. As tension builds, and relationships begin to crumble, they realize that only one can make it out alive. Could you trust your boyfriend? Your girlfriend? Your best friend? Only one can go home. So who will be the last man or woman standing?