The concept of the game was very cool! Scaling up and down was front and center, and there were different design elements in the levels and foes to make them work well.
The gameplay did suffer from some hitbox issues - especially lingering hitboxes from projectiles, and mis-sized hitboxes on some foes. A lack of regen or checkpoints became a small issue near the end as well.
Edit: Also, occasionally, foes could leave a room with a locked door and prevent it from unlocking, softlocking a level.
There wasn't much story to speak of, but what little was there actually fit quite well with the retro style that the game was going for.
In fact, the art style and music were very fun additions to the theme. Although the music was rather quiet compared to what I'm accustomed to, the songs are fun to listen to. Also, the theme of the game is integrated really well into even the title.
Overall, it was a very fun retro-style game concept, and I enjoyed playing through it entirely!