I played your game as well:
Sound
The sound is really loud even when turned down to the lowest settings so definitely needs changes made to get that sound score up, the alarm almost blew my eardrums with the headphones around my neck at 30% haha.
The sounds themselves are good though and fit the game well so keep what you have but just let people adjust it more as there was very little difference between 10% and 90% and 0% music doesn't mute the music which may make some raters unhappy.
Difficulty
I noticed on level 5 and 8, its was quite hard to make informed decisions on when to use rewind and the direction to choose because I'm having to plan for pathing up to 7 moves ahead across more than one enemy as well as my own redirection. For me that turned it into more of a guessing game than a strategy game as my overworked brain was fried trying to virtually map it in my head.
Level 8 was the killer for me, I really couldn't figure it out at all and didn't manage with brute force, is that level definitely clearable? It was made worse by the fact that the same square can send me both directions depending on whether I used U before the guard moved or after meaning there were twice as many combinations I have to try.
Clarity
Do the numbers on the ground have a deeper meaning beyond signalling which direction the player will move? I'm not sure if that's a big piece of the logic puzzle and I just didn't understand such as some sort of 'calculation' I could make around enemy pathing.
For me I think I just need more information so I can feel like I'm in control and making conscious strategic decisions rather than brute force guessing, on the other hand I might just be too stupid to make sense of the game.
Art
The art is pretty basic but that's because the game is focusing on the actual mechanics over environment so no issues there for me.
Controls
Control instructions were clear and easy to remember, maybe change the U button to something closer to WASD as its the only control that involves having to move your left hand
Improvements
Outside of what I've mentioned above, these are just the thoughts I had while playing:
At the moment the game focuses a lot on forward playing a lot of moves ahead, what about designing some levels that use the environment such as a 2 square wide level where you have to use U when by a box in order to hide behind it, something like this then gives you a real reason to build on the mechanic over time by allowing 2 rewinds rather than 1 etc.
Add a menu while in game, I wanted to skip level 8 and check out level 9 but when I pressed esc it just exited the game so I had to reload and re-adjust the sound settings which isn't ideal.
I hope this feedback is useful, it was hard to make feedback because I struggled with the core concept.