I'm trying to be restrained and honest in my praise and give ideas for improvement, but for this I'm just going to tell you to keep going. Really, really great fucking work.
There's no point in pointing out the "faults" here, because there's always a million of them in a jam game, and here they don't stem from bad design decisions but a lack of time. What I mean by that is things like visual feedback, pacing, balancing, etc. and those are areas you obviously are going to succeed at judging by what you managed to pull together here, so again I'm not going to comment on that.
What I am going to comment on is the combat, character and enemy design, because wow. So much thought put into them, way above any of the jam games I've tried so far. The way they're combined to counter your instincts as a player without being random works so well, I was giggling to myself out of joy as I was playing.
Example: the room where you enter and there's the spawner mobs along the top wall. If you go in defensively, and retreat when all the other mobs surprises you, you put yourself at a disadvantage. The mechanics encourage you to be aggressive (Souls-like), the back cannon is a genius early addition to help with that, so to get the upper hand and to kill enemies fast enough (spawners put a time pressure on the situation) you need to get the most out of both guns, so that means towards the center of the room. That means dodging bullets from all angles.
Even if you do manage to kite them along the wall, or shoot from a narrow hallway, the way the different enemy types act means they will quickly overpower you. At no point did I feel like I could outsmart them with my "gamer brain", I had to outperform them. I had to take risks, and got rewarded for it.
And this is where the take on the theme works so well. You've incorporated ideas I've seen in many other games here already, but here it just clicks. I'm genuinely interested in seeing how changes to the cell is going to affect the flow of combat, how it's going to change your priorities.
There's a bunch more here to be impressed by, on so many fronts, but I'm out of keyboard juice. Good luck continuing on this title!