Great job! Concept is really unique.
Pixel art is simple, bright, and fun. Only possible suggestion to really "level up" it would be to try to style your enemies to different exception types. Also, background could need some texture, if you're moving away from the core.
Music is a nice chiptune banger, after a while I started to feel like I've been plunging into a deeper madness though. If you're planning to update it, play with the music more and add like two more.
Overall solid job with them on your first time!
Also, managed to beat the game after an hour of different strategies. Feels like I've cheesed it... More UI elements on later stages is a must