Thank you for your detailed feedback!
My initial idea was that the dungeon would be looped and you will come back to old rooms and the enemies would become stronger each time. It felt wierd upon testing so I scratched that idea and went with more linear level design. I agree that some of the levels don't make sense in the beginning.
I agree that resetting to game is harsh, but the game is extremely short anyway, so I didn't bother adding any checkpoints.
The amplifier interaction with past copies was accidental and I was surprised how well it worked. I'm planning to add more past-self interactions in my postjam update for the game.