A really useful API that can be implemented into the engine are 3D Splines. Splines solve many general problems. Its not a niche thing that only few developers would benefit from it, I think that is where it provides the most value. A 3D Spline API could be used for dynamic npc path finding, paths for environments, or really cool visual effects that utilize complex paths like twists, knots or loops. I have an example system that I made for my game that shows how Splines can solve general pathing problems so that developers wont have to do hacky algorithms to find solutions.
This is a grind railing system I developed. A weakness of it though is that I cant make loops or twists accurately, so I have to make these strange pseudo-loops. They work just fine and I am still very satisfied with the result. However, some cool loops/knots would be awesome for future updates.
This would definitely help developers for Sonic games on the platform, as they’d want to force movement in specific directions in some parts of their games (Using splines) just as normal Sonic games do.
Here’s an example:
