There's so much game here for a jam game, wow!
First things first, let me say that I am in love with the graphics and the general tone/aesthetic! I especially love the pixel art monsters and (what I think are) pre-rendered weapons sprites. Everything looks so good, and I feel like it all gels really well together. Also, there's some fancy shader work here with the CRT-style distortion -- really nice touch!
Also, like -- it's just fun. It's weird to me how different games can feel when built in the same engine, but for some reason this just feels really fun to run around and shoot in. It never felt frustrating to me, and honestly if you expanded this into a bigger, non-jam game I would play it, I think it would be fun as hell.
Oh, and the sound is great too. I feel like I'll be saying "It'S a WaCkY mYsTeRy OrB!" randomly for the rest of the week, so thanks for that lol.