Actually a marvelous game, @eucariot ! Took me a moment to realize you can wrap around the edges left or right to avoid pits.

I would consider adding power-ups where each of them are only active a short-while, say 4-5 seconds.

1. Shield: Don't lose a heart when you hit the bottom. Does not vanish if you hit the bottom. Still only stays active 4-5 seconds.

2. Boots: Run double-speed for a short while. Can outrun the moving holes.

3. Warp: where the game runs half speed giving the player more time to think.

4. Sword: You can attack the monsters. Have good animation of their upside-down sprite falling vertically down through the floors.

5. Wings: Player does not fall down.

You might have 1-powerup appear for level 1. 2 for level 2, 3 for level 3, etc.

In any case, well done. Gold star work !