The art is really good. The all audio fits well with the game too. I especially liked having the BGM silent before the final fight. The variable jump height is a great addition. Having the time slowed down when receiving damage is really cool too.
I think that the gameplay still have room for improvement. The movement feels a bit slippery, but which is fine since the game is short and doesn't really punish the player for their mistakes during platforming. I would personally prefer the levels to have more head space so that I don't hit the ceiling so often.
One bug I found is that the player's health doesn't get recovered between playthroughs, so if you died and restarted the game, the player will die immediately.
Overall, it's still a fun game. Great job on it.