Hey there! I just picked up Fusion from Humble Bundle and started off with the Custom Platform Movement tutorial by DavidN. I seem to have it working pretty well, with one exception. Sometimes when I collide with walls (primarily from the side) I stick to them like the Spiderman. Sometimes some wiggling will dislodge the player, but sometimes it just sucks him further into the wall. Which is, needless to say, not what I'm going for.
Initially it seemed to be caused by catching on corners of the sprite, so instead of using the sprite as the player I made it an invisible square, and had the sprite follow the square around. Which helped a lot, but it still does happen sometimes. So now I'm not sure what the issue is. I've also tried checking the "Collision with box" option on my platform, which I read helped someone else, but had no effect for me.
It either happens exclusively to the left, or most frequently. In addition to jumping into a wall and freezing there, you can also walk straight left and stick into the wall, becoming unable to jump (but can free yourself by walking back right).