More figures like the Stickman. And some sort of on contact explosive, that you could drop that would explode. It would be a solid but be movable/droppable.
Well it's hard to code. When someone did code it it either went as powdered solids or made black hole look like soup. No more stickmen because there's no real point. It'd probably be easier to code (copy stickman, make the controls WASD, ect) but there's no real use.
What about Zero gravity magnetic field? it can fill the empty space by default, or it can be spawned as a gas with big impulse, but low speed, not letting anything that hits it to fall down.