Man, this game is amazing!
A small big bug tough: there is a level that has two islands up and two down, in simetry. The inferior islands have spikes on the inferior side. This level has two of those bouncy slimes, one up and one down to let the player change between the platforms, but at some point the slimes just decided to have a walk to somewhere else and got out of the screen. I was still able to complete the level without them, though it was a little more complicated to switch between the inferior and superior islands.