Nice work for a first game jam! I guess you're a solo dev, so it's understandable the lack of sfx. A game jam alone can be overwhelming.
The idea is cool. Specially if you're interesting in continue developing, could be a great game.
You should improve the targeting/shooting system. Took me a while to destroy all the turrets, even when had all the other ships with me.
Great job! Congratulations!
Please try my game if you can :)