I really like this game because how you managed to make it in 3 days and how you took the twist of both themes! Great job and impressive for a jam. Good Luck!
Some feedback (constructive):
I think that after a while (at least for me) the audio started to get really repetitive. This means that the music was going over and over and the SFX were the same. Maybe, instead of a pew,pew,pew,pew, you could add a pitch randomizer and it would be like PEW,pew,pEW,pew,pEW. That would definitely make the game much more interesting and less repetitive.
I think that this game could be really cool as a multiplayer game. I also think that it would cool if the enemy's could shoot at you back because I found that the only way to die (for me, an epic gamer who's in milk gang) was if I shot myself.
I really like that this game has a high-score, but I think that implementing a public high score would add some competitiveness to this game.
Great game, I really can't give much feedback, its a really solid game. Congratulations and good luck!!!