Really cool game! The echo mechanic is very cool. The visuals also look really nice.
I almost finished the entire game but the last levels were a bit too difficult for me. Maybe make the stun cost 2 charges instead of 3? Now you have to wait so long before you can stun, and at the start of a level you can't use it at all. A fullscreen button would also be nice, I wanted to be more immersed! Some sound effects were also a bit loud, a volume slider would help.
Very fun game, well done!