Only W,A,D are available for movement.
This engine was designed by me. This is free to use in a project for movement, but please credit me if you do end up using it. Feel free to remix this into a platformer if you want, and change the background, edit the code, etc. The jumping isn't the best but at least here it is. And I got a bit of the slowing down higher up. Luckily there used to be a bug that you could 'double jump' or hover in a way but that is solved.