This was pretty cool! The effects are really nice, I liked the rewind one especially. It is a bit annoying when you die and go all the way back to the beginning for like a third time, you could have made the player return to the last place they were standing on before they died, and that would still fit the theme. It was really satisfying to collect the little orbs by killing slimes and breaking stuff, and the sound effects are well made. Only problem with the orbs is that I had no idea why I was collecting them.
The atmosphere of the game is really cool, it feels like you're trapped in a place and in time. If you were to expand on that with some story it would be awesome. The movement is alright, I kinda liked how the jumps are really long, but the acceleration on ground is wayyy too slow. Cool game!