Battle Royale mod for Half-Life 2

42 students have been chosen by national lottery to participate in the BR program. The premise of the game is simple: the students kill each other off one by one until there is a sole survivor. Each student is fitted with a metal collar that tracks where they are, relays their vital signs, and records their conversations. It serves a much more sinister purpose. If the game runs past the allotted time limit, or if a student enters a forbidden area, a small explosive nestled up against their throat explodes violently.