Great game! Vibes and mechanics work really well together! Some thoughts (I'm a game designer by trade, however please take these comments with a pinch of salt as I'm sure you're thinking of many ways to work and improve in your own awesome ways!):
- First two levels drag on a little bit, since the variety in enemies is low. Consider making them a bit shorter.
- Love that shield makes you invulnerable for a fixed time, super useful when dealing with frog tongues coming at me! Makes me take more risky actions!
- Powerups overwriting each other when picked up means there's less player control. I might have 5 seconds left of level 3 shot powerup but it gets overrided by a shield, and it feels like I'm being punished for grabbing a powerup. Maybe a 'pocket' for you to put spare powerups when one is active would alleviate this issue?
- Having the Rhino bump into a certain wall at a certain time could reveal a secret room? Or flood the map with enemies? Rhino (and Frog) are super interesting as you can force them to interact with something based on your position, therefore tricking them into helping you do... something cool?
Great work!