Stumble upon Rumble is created with a sandbox structure in mind. This means that other game modes can be added easily. This could expand on the existing fighting game, for example by adding team-based fighting modes, battle royale / free-for-alls, and more. But it could also mean adding new game modes entirely. Basically, anything that's suitable as a 2D game can happen. Whether that's a platformer, a 2D racing game, hide and seek, or just a flappy bird clone, we can add it.
Eventually we hope to open this up for User Generated Content. By having the users provide the game with new content and game modes we truly decentralize the game as it would no longer depend on our work. It would also make the entire ecosystem much more dynamic, as users come up with clever new game modes and are monetizing it directly.