Thanks for let us playing your game, there are really great stuff in there, I have a couple of feedbacks:
1. Obviously the puzzles are just first draft of ideas and are unpolished and I'm sure that you are aware of it but since it is really important I mention it again that the levels shouldn't be in a way that a tiny mistake would cost you to use retry button. for example the structure of the rotating doors are is a way that would easily make you left behind the door even with the magnet in hand and of course if you lose the magnet in some part of the level then most likely you have to reset the level. there are for sure a couple of solutions for this and I'm sure you will find the best one for each level.
2. this one isn't critical but I think finishing the level by finding the key is a little bit anticlimactic because you would expect to use the key in the level itself not using it in the hub area.
3. if the hub area is going to be like this in the actual game I would expect to use r2 to sprint for better feeling at navigation.
4. I understand why you choose the approach that for opening the doors in the hub player needs to use the magnet but I think it is annoying and I don't like it.
5. I like that the level are designed in a way that you don't need to use timing or accuracy for throwing the magnet and I think it is really important to keep it that way through the rest of the game.
6. the above point should be the case for platforming as well. for example I don't know why the gap in the last level (between the magnetic field) is in a way that it is hard to jump from side to side.
Keep up the great work Mark!