Kill Theory (2009)

"Kill Theory" falls into the group of movies in which a single stranger forces a large group to do horrible things to each other with the promise that one of them will be able to leave the horrid event alive. These other films include "Vile" and "Hunger".  In "Kill Theory", a group of friends are forced to turn each other to prove the point that sometimes you have to kill your loved ones in order to survive. The unseen killer had been convicted of manslaughter when he had to cut the rope and kill two or three friends below him while they were out mountain climbing. To prove his point that he was innocent and had to do it, he finds a group of friends out at a remote summer house and sets up traps to ensure that they don't escape and are forced to play his demented game. As always, favoritism comes up as well as feelings of being bullied and former flings come to light, testing the loyalty and will power of the group. Some die early on while others stick it out and last longer than you might imagine. The movie has some heart churning moments of betrayal and keeps things interesting. Most definitely worth watching at least once.