Played it and it was very interesting! Though I must say, the aesthetics, while good, took me a while to get used to. Perhaps it could be me? I dunno.
For example, the gray ledges that you can stand on are a little too dark and easily blend in with the bricks around it. Speaking of the bricks, they could conversely be darkened. Furthermore, the palette the one-sided walls for wall-running that you can and cannot get through have a palette that looks similar when you wall-run along them, as the palette for the former wall blends in with the BG and whatnot. Try making them more distinguishable.
Edit: Also, in the part with the first P-Switch, you can get through the helper ledge under the wall triangle adjacent to a P-Switch ?-block wall to run through.
--------------------My Mode 0 guide.
My Discord server.
It has a lot of archived ASM stuff, so check that out!