Some tips:
There are fake walls, and they look completely identical to normal walls... Hint: look at level boundaries that seem thicker than necessary. Rockfall Reloaded is one of those levels.
If you're playing Switch or Cube and you think "maybe I should make a map?": yes you should...
Five, Time Glass, Breaking the Wall, Weir, Mellon: Yes, surprisingly, they're actually possible, without getting new abilities... (other than the one at the end of world 1).