Very solid design, everything here is awesome and fits. Especially lack of tutorial, I mean direct, hand holding tutorial, just a simple levels to figure things out before throwing the player into the harder parts.
Hope You'll expand! This can be done with flipping reverted moves horizontally, or making safe zones, breaking the sequence. Or adding moving platforms that every turn move, or teleports. Or adding evil character that follows the player.
I feel that the skull tile wasn't really necessary, outside of that one level with a block on top of it. This was maybe one and only flaw I've found? Great game