I've been thinking about this for a while, and I believe, with a little brainstorming, we could come up with a good Floor is Lava game at the gym. Right now I'm thinking of a turn-based game. This is what I have so far:
Two types objects to keep you off of the floor: Checkpoints and Throughpoints (I know it's not a real word).
I think checkpoints can be anything trivial to stay on (such as a vault box). When you touch a specific checkpoint, you must end you turn there, although you don't need to end your turn as soon as you touch it. You must end your turn on a different checkpoint than the one you started your turn on.
You may touch any throughpoint any number of times on your way to a checkpoint. I believe these should be things that are difficult to stay on (such as precision trainers).
If you misstep while it's your turn and you touch the floor, you must go back to your original checkpoint and your turn ends. You also lose your next turn. In the case that someone touches the floor while it is not their turn..... I'm thinking they lose their next two turns, or go back to the previous checkpoint they were on and lose their next turn.
In this game, the lava monster wouldn't touch the floor either. The goal of the lava monster is to get on the same checkpoint as someone else, in order to get them out. If the lava monster touches the floor, he or she goes back to the original checkpoint, and loses the next turn.
I'm sure it needs some work, but this is what I have in mind. Tell me what you think. I'd like all of us to create this game.