When I made Pkoo's adventure 2, I realized that the wall slide sprite had an extra pixel that wasn't supposed to be there. That explains why when wall-sliding, it is bumpy and the sprite switches between two costumes. It was supposed to just use the wall slide sprite and not be glitchy. Press space to switch between old (glitchy) and new (un-glitchy).
This may or may not be a Pkoo's Adventure 2 preview/teaser.
