Really well done for a first game! Only thing I would personally change is the pace of taking a turn but as it is now is highly tactical which is not at all a bad thing :) I also love the upgrade system and ability to configure the ships as you like.
Here are some random ideas that I had while playing that have absolutely no consideration for game balance:
- Mirror-breaking flak cannons
- fog-of-war
- disco-ball asteroid
- destructible "hull armor" blocks
Cheers, and great job on the game jam!