This is the kind of pixel art I look up to. No notes, just completely clean work that knocks my socks off.
The fact you all pulled off 4 player capabilities during a game jam is honestly impressive. Honestly, this is the stuff I dream of working on someday.
Some notes:
I do wish the "READY UP" screen had keyboard control prompts. This will probably get less relevant in context in a different environment.
If you hold the fire button down, the default gun shoots at a very slow rate, but if you spam the button you can get a higher fire rate. I'm not sure if this is intended or not, but it makes some of the other weapons with limited ammo less useful.
The initial spawn screen where you learn the controls is a little strange, and I'm not sure I fully got it all before it started moving.
Additionally, the size of the rooms are a little claustrophobic with one person, so I don't know how readability would work with 4. The references were also a bit too inside baseball for me, I didn't really get it.
The fact that I'm basically nitpicking though probably says it all; this is a really well made game. This is basically finished and ready to ship in a cabinet. Props to the team!