The Plaza PVP games, like Chainsaw Deathmatch, should give a small participation bonus for sticking around till the end of the game. Maybe more depending on how long you’ve been in?
The PVP games are definitely less popular than the target or grab ones, but sometimes I want to play, so I join anyways in hopes of getting something started. Two minutes later, still no one joins, the one person in gets nothing for trying, and the announcement claims that no one participated, which further fuels no one joining. I think a small bonus would get more people in and, at the least, reward someone for attempting to play.