Algodoo

We already kinda did DRTTB so we're doing a comment suggestion instead (sorta)!
The original idea was by TransformingRobot on Day 5's upload, although I had to modify it due to how Algodoo handles collisions, so instead we end up with this.
Each marble has 10 HP. In order to deal damage to the other contestants they must hit the red circle in the center and then hit another contestant before the time given in the bottom right corner elapses, otherwise they will harm themselves instead. There's also healing circles on the outside, they activate after 2 minutes and have a 1 minute cooldown.
Oh also, THIS IS THE REJOIN EVENT! The eliminated contestants will participate along the active ones. The last surviving boot rejoins the game!
Press 1 to start.