I was thinking of something that could lead to interesting maps and I had the idea of being able to change the gravity. It could work by having an invisible box that when players are inside it changes their gravity to left or up right for example. Exiting from the box would bring their gravity back to normal. I don't think something like this would be very stable with speedrunners though.

Also it would be cool to have water in speedrunners and being able to run on top of it when you're going faster than normal.