Thanks for playing! I cracked up the first time I heard the death sound effect and knew we had to add it to the game.
I definitely agree that there being no residual effects presents problems. In a game like Slay the Spire, managing your remaining life adds some interesting choices and risks to fighting, whereas here you basically want to fight any ship you can. I had planned to add actions that permanently remove a card from your deck, as a form of persistent damage, and may add this in still in a later update (after the jam).
I personally like the level playing field of the enemy having a similar deck, but you're right I'm not doing enough interesting things with it to justify it. Maybe draft rewards could come directly from the enemy's deck. I also would have liked to add more cards that might have effects based on the cards the other player has.
Thank you for your feedback, it's very helpful!