the art is simple, and some mechanics like parts to modify the player is really neat. some level design was a bit... too difficult? one area in particular was level 2. the autoscrolling is neat but the area with the first turret is quite miserable without double jump due to both the bats and the turret and very precise jumping being required. that though is just my personal thought on its difficulty, but as for the game design, one major issue was the fact that the autoscrolling has no barriers at the start or end of the camera. i was confused and jumped off a cliff at the start because i didn't realize it was an autoscroller because the camera only moved after a few seconds of waiting, and had a barrier been there, then it would have both prevented the fall as well as made me see clearly first it autoscrolls. you can see this used in games like super mario bros 3 in its autoscrolling levels. another critique would be turrets. because they angle at the player location before shooting, it makes the visual off in that a bullet would be fired but then the turret immediately faces another direction. stopping the movement for a moment to fire and then wait and then continue rotating would make the turret visual feel a bit nicer since it is required to be looked at in order to avoid being shot.
the levels were fun on their design though and the music was nice. some changes just would make it a little nicer and more smooth and overall feel better to play. regardless, nice work!