The margin for error is very low with this game. If I screw up a reload, or miss a shot, then I'm definitely going to get overwhelmed and die. I'd recommend having some sort of forgiveness / health mechanic, so that the player doesn't lose instantly the first time they screw up.
Also, nice job on your first jam! It's definitely a stressful but wierdly enjoyable thing to do. Looking forward to seeing more games from you in the future!