I really like how the majority of the puzzles are designed so they can be solved without holding the player's hand in any sort of way. It helps having some of the notable objects color coded in a neon fashion which really contrasts with the plain white walls; that is a great design choice.
The rewind effect showing all the player's movements is also really cool, but it is a bit too slow if I wanted to rewind all the way back. Perhaps the rewind could be controlled with the number key inputs so the player could have the option to either rewind slowly or quickly.
Unfortunately, I ended up getting stuck at the level where the lava blocks come down. I didn't figure out that I was supposed to close the doors, lock it in place, and rewind back until it was too late to rewind back. Perhaps after the player makes it to each checkpoint, they can have the option to restart from that point in case something like this happens?
I'm also not particularly a fan of the lava sending the player 30 seconds back. I would have preferred if the lava burnt me into a crisp and not allow me to move since I'm dead, with the option to rewind yourself back to the state where you were alive.
It's not too often that you get to see a first-person puzzle game that allows you to rewind time. I'm hoping you can continue on with this project in the future.