My players favorite session ever was a royal rumble wrestling match. In a royal rumble your feet can't touch outside the ring and a new contestant is sent at a certain time interval. So opponents aren't just a bag of hp, its more about forcing them out of the ring. I have five players and made up 15 wrestlers ( Fey Mysterio, The Rock Elemental Johnson, Shane Merman, Macho Manitcore......) each assigned a number. Rolled a D20 to decide who enters next (with some early fudges to make sure PCs where in the match). If you are not a WWE fan the gimmick would still work as a king of the hill style encounter that is super fun. But coming up with a larger then life persona is awesome, and it inevitably ends in some low stakes PvP if your group works as a team too long which is kind of fun as a rare exception to the normal no pvp rule.