A group of high school kids formulate a suicide pact with a macabre twist; they will kill each other in a game. Everyone writes their name on a single piece of paper and signs in blood, for blood. Each one is given a dagger and on the designated day the game starts.

Each on gets a torn piece of the paper with someone else name on it, which they must carry. They seek and attempt to kill that person before they are killed in the fatal circle. Then they take their victims name and continue. Only one will die a winner.

This may be more of an arena-type event but that depends on the inclination of it's guests to make drama and dialogue, plus alliances and such. 

I also see a few issues: metagaming (when people use things they know instead of what their character knows to play) could hinder secrecy. That can be fixed with posting to a third party moderator (yours truly).

People don't like to die. though that shouldn't matter when participating in a suicide pact. It could be moderated or players might just straight-up outsmart each other. I will make sure you're small environment is detailed. I also enjoy the fact that this story has an ultimate end, you don't see that very often!