I really liked the art! The game has great colour schemes that work well together and beautiful sprites as well as fitting effects! However I felt that the combat was quite lacking in any depth, and therefore wasn't much fun to play, after my first death, I just ran through the game without even touching the enemies at all. Here are some critiques that I would give:
1. There's a health bar indicator, but there isn't much to tell the player that they're quite in danger, maybe adding some like flashing red on the screen or making a sound distortion effect of some kind when being hit?
2. It isn't clear when you've hit an enemy, maybe make them get knocked back when they're hit?
3. Movement was quite janky and I often got stuck in walls
4. There's isn't much indicating that the player has gotten stronger what so ever. The hits feel the same. You could try showing the players precisely how much damage is being dealt so they know how significant the batteries are. Or maybe making stronger knockback based on how many batteries you have, maybe even some blood splatter if you're okay with a bit of violence.
To conclude, the game is a bit lacking in code as well as design, but I won't say much cause I ain't much better off myself either lol. Just take this as constructive feedback, from what I can see, your art is superb, and you're on a fast track to improvement! Keep it up, I look forward to seeing what you make in the future!