Wow I had so much fun playing your game!
I was impressed by all the visual polish you were able to complete as a solo dev in the time constraints of the jam. Some of the highlights for me were the mini map in the top left (first game I've played in the jam that implemented that), the particle effect explosion of the enemy ships upon destruction and the rocket reload meter in the bottom left. All of those little things add up to make the game just much more readable than if they weren't there.
I loved the rocket launcher especially how powerful it was on the red ships but the long reload time kept it balanced. I found myself taking extra caution when lining up my rocket shot because I knew it was going to be a while before I could get another one off haha.
As far as feedback for improvement since you mentioned in your game page you will continue developing (which I strongly encourage it's a great project) I will add that I accidentally clicked an upgrade when it popped up because I was madly trying to take down some enemy ships. As skykone suggested pausing the gameplay during upgrade selection and creating a very small time window where clicking would not select the upgrade could avoid unintended upgrade selections.
Keep up the great work and really enjoyed your game!