Hey, the visuals look great. Good work with the post processing. I love the ghost visual during rewind. The screenshots made me open the game, so kudos. Now for technical feedback, add some feedback when a key can be pressed. You as a developer know, but the player doesn't. CodeMonkey has a great tutorial on interacting with objects on youtube. Check it out!
Than explain the objective to the player. I tried collecting crystals and died. And didn't know why I died. With better introduction, your retention will go up. So when updating the game - explain the goal to the player ingame, add feedback on when something can/can not happen(Lets say if a door is locked, say to the user "The door is locked"). And some visual feedback near the crystals. What changes when you get to them?
If you decide to improve upon the game, do reply to me and I will play it again. Kudos on the submission!