Very creative concept, possibly my favourite game this jam! I honestly love this type of game. You also explored the core mechanic very thoroughly with a lot of other ideas. It makes it very immersive that you let the gun affect everything, like yourself and the death counter. 
I also noticed how the timer only starts when you move, which is a problem I had in my own game that I solved differently.
To improve, the game could be polished further in some regards; the controls for platforming could be improved, and the game could be a bit more responsive, like camera shake when you shoot, or give clearer feedback when you die because you ran out of time. (which is very understandable for a jam game)
I know someone said to consider focusing on the puzzle appeal, but I would actually argue that you could have also pushed further the other way. I enjoyed solving the puzzles the way you intended; however, I could tell that you had left further ways of saving time, eg speeding up certain walls or slowing down the death countdown, which I found weren't really necessary to complete the level with the time provided. I think it would be good to find a way to reward players who make use of all the mechanics properly. Maybe by tightening the time provided (which may have come from more playtesting), but you could also add optional goals, or anything else more creative.
The puzzle design was very good; I like that you guided the players towards solving things for themselves.  I personally like to only introduce one mechanic at a time in simple levels and reduce the complexity to prevent the player from getting overwhelmed or reduce the chances of a player getting stuck on something they don't know, then put everything together later.  I think it was perfectly manageable the way it was, but maybe to perfect it, I personally would consider only having the moving platforms on the first level but the death countdown on a different level, or the bouncing surfaces having their own level. 
Sorry for writing so much.
Great entry, though. The game clearly has a lot of potential for both puzzles and platforming!

Oh, you used Penusbmic's art, nice!

I loved how the mechanics were taught the player and they were allowed to figure out how to use them without hints. Extremely clever concept, great art, atmosphere and vibes, definitely a 10/10

Really cool puzzles, my only complaint is the platforming feels a little off. Some of the jobs feel a little too precise for a puzzle game. Mostly a personal preference but I dislike when I know how to solve a level but I have to restart a few time because I can't quite nail a jump

Really interesting puzzle platformer. Gave me Braid vibes. I really like how the level restart timer was also an element in the level that can be sped up or slowed down. I liked the art style and music too. Maybe you can add more time altering bullets later, like a bullet that reverses the objects time or a bullet that switches the countdown to two objects. 
Overall it's an exciting game...great job. 

really really creative and fun, great legs on this, continue working on it!

Really cool game I just wish there was a preview or something when shooting speed up or slow down beam, to know where it would land

Very fun game. The art was great. We actually considered this name for our game as well

Really cool and interesting puzzle platforming! beautiful artstyle, and a real treat to play! Amazing work guys!

Had a lot of fun playing ! Love the time bullets mechanic and the art too. But, as a poor aimer, I would have loved a little preview on the bullet trajectory, especially when it bounces. Might be optional so people that want challenge could disable it.

Great idea. It is hard but rewarding. Each level is a bit of trial and error. The time manipulator gun is genious. The effect looks good too.