Ok so 2 ideas that I had but wont get around to making myself.
1: Advertise the server as a "farm server" but its really just a farm with a sheep pen. The players are the sheep and one play is the sheep dog that you can dress them up with outfits they cant take off. Give the sheep dog a KB stick and they have to get all the players back in the pen before a timer runs out.
2: Wipe out mountain: So make a huge teraformed mountain that players will have to parkour and path find up, but litter it with custom traps kinda like the show "wipe out" and make it into the race with the last person to finish gets banned for a day.