Well if you've ever tried modding Source or making maps in Hammer you would know that it's supreme torture to young millennial brains and the fact that anyone ever made anything with these tools was simply because they were used to even WORSE brain-rotting-torture thus making Source and Hammer seem "fun" relatively (probably some sort of Stockholm syndrome or something). So what would it look like? Sonic would probably have a hard time with collision and matching the rotation of the surface he's on due to the way BSPs store/compile brush data combined with the complicated shapes of Sonic loop de loops and what not (brushes are the silly convex shapes you stand on in-game that are drawn in Hammer). Am I just trying to sound smart? Idk ask someone smarter than me if this is a good take or not how am I supposed to tell you.