Thanks for the feedback.
The camera will definitely be changed. I might ignore the whole Game Boy thing with only two buttons and have the player pan it manually just like they can look up or down.
Not sure what you mean by restart button. Restart the level? killing yourself is usually quick and easy so I don't see why that would help. Restart the game from level 1? Yeah, that's necessary and will be added, along with level selection.
The charging enemy is pretty tough, I agree. It's just using a raycast right now for checking line of sight. I'll expand that to a thin trigger zone in front of it. Should defuse it a little.
The metal wall in level 3 is a bit of a troll to try out a mechanic. You're supposed to first hook onto the enemy from the left, change direction and hook onto the ground behind the wall. I'll remove that, I don't think that mechanic should be mandatory.