I've always enjoy playing game in this genre and this is no exception.
I love how you assembled the asset, looks really nice and that transition from 3D to "2D" feels really smooth and satisfying! A bit more visual clarity on the turrets will make it even better, perhaps just a glowing outline will do.
The game started of being manageable hard but then it just gets too easy at the end. Having some difficulty scaling will keep it fun for a longer period of time such as adding various types of Asteroid, like rubble pile (which will break into more parts), metal asteroid (with lots of health), etc or maybe even space ships hahahah. Turrets can have various upgrades too that does each unique effects. Anyways it's just some ideas that pop up when I was playing, but yeah for a solo game jam, you've did really well!
Overall it's a very solid game with lots of potential, well done game! Keep it up!