I was thinking of having more supernatural elements.

The idea I had for these RPs were two demons having a competition. They would each create a game, and then the other would pick a group of heroes, and they would have to deal with the other's game. Whoever won, could gain some amount of power or something of the like, and in the end, the goal of all the heroes together could be to kill the new overpowered demon. 

Any one else have ideas?