I think it's a really, really polished game jam game.
It's polished to the point where I wish it was even better, actually. It has so much potential. The game loop is a lot of fun, and it has a lot of addictive qualities that I think would work well for a full release for an app for instance.
Where I find it falls a bit short is how the difficulty is designed. I don't like that the rockets are gray with this tiny triangle for visibility. Using these visuals as a type of difficulty design I think takes away from the experience. Because if you made the rockets entirely orange or white, you could push the difficulty curve of the introduced mechanics more aggressively.
This is where the game became slightly dull for me. I got to level 10 and at that point I felt like I had gotten so many powerups that I could survive most stuff. The damage I took was from not seeing the projectiles due to the dark gray design. So, the difficulty isn't really coming from the game mechanics very much, but the visual design.
One more thing I think could have been better is the placement of the timer. I find that having the timer dead-center of the game messes with your perception. You really need to stay alert of your surroundings in this game and having a timer taking up screen space with projectiles zipping over it, is an unfair design choice in my opinion.
All these feedback points comes from me enjoying the game and seeing potential in it. Perhaps it could be useful to be taken into consideration if you push this further some day in the future.
Cheers!