Very fun little game. The feedback is especially good, the addition of screen shake and the sound effects make the ship pleasant to control. However, the core gameplay loop is pretty linear as mentioned by GSgamingking, but for a game jam that’s still good!

Great work!

I think adding a ammo system and a ammo upgrade would be better as rn player can just press space and endlessly shoot at the enemies.

I think the game would be fun if I knew what was happing. It seems to be an arcade shooter-style game where you get random perks/buffs (I assume that is what the cards with different graphics are). I would recommend giving the player info on what the perks do and how they affect the player. Well playing I also couldn't play for too long without the cards popping up and stopping gameplay so I would recommend making the threshold increase based on how many upgrades you have. 

The game controls well but I don't think there was a difficulty curve of any sort. You could make it, so the enemies shoot more often and make less of them increasing how many there is the longer you play. I think the game could be a lot of fun it is just lacking a few things to make the gameplay clearer and more satisfying to play.