>>724992351
Two enemies trying to move into the same spot at the same time will kill each other (but it has to be the same spot, not the spot where the other is currently standing, so for example, two leeches with 1 empty block in between them will kill each other the next move, but not two leeches right next to each other)
Opening a chest makes you face downwards
Many puzzles are more easily solved by working backwards from the "solution state"
Many puzzles can be solved by creating a "magic carpet" (a 2x3 or 3x2 set of tiles). With it, you can go anywhere. A miniature version (1x3 or 3x1) can move you vertically or horizontally.
There are ways of making all puzzles easier, but that in itself is another puzzle.