The idea is pretty cool, funny I made a game with a similar concept where you switch between worlds :D
The rewind mechanic is pretty cool btw! Makes the game a loot less frustrating.
But I see you took the approach where you have 2 entities and the player can switch between them, I had 1 entity which can switches worlds.
There a few bugs I found (some I don't know if it is intended but I still write it as feedback):
- When you rewind, only the active entity is rewinded not the inactive one.
- The white entity is dying by things that are in the black world (the cactus thing on the left of the start in level 1)
Sometimes a box get stuck against a wall and I have to restart, I would also add a pause menu or a restart button so the player don't is hard stuck to restart the game.
Also I would suggest to redesign the boxes that exist in both worlds. For me it was sometimes confusing why they are not moving, till I realized it stuck against a wall in the other world.
Awesome work keep it up :)