I'm thinking of an anime that I my roommate used to watch and was pretty cool.
It was about these random people + a dog that all get teloported into a room. And in that room theres a machine that tells them to go kill people if they want their freedom back. So basically, the people have to get a 100 kills to be free, so each night they go on a mission and go kill people and stuff. It was pretty graphic.
I know the description is little vague but only had glimpses when my roommate watched it.