Good game and I generally enjoyed it, but I have a couple complaints.
The movement feels a bit slow and the jump feels a bit short
I think going back to the door would be better than suddenly teleporting when grabbing keys
Keys not showing up in levels after completing, it would be better to have a little ghost key in case people want to replay levels
The cooldown for switching polarities is long and messes up the flow when moving fast
Pressing f to change polarity is annoying to do while moving, could that be swapped to right mouse button or shift by default
Doors grabbing the magnets from your hands instead of pulling you with the magnet
Can't move while aiming, but can still jump
Not a complaint, but the levels are almost pure puzzle, I would personally prefer a bit of platforming or more use for aiming.
Ps. Hold control in the lobby for a "little" surprise