Retro-shooter rogue-like is a pretty unusual gameplay compared not only to other jam entries, but to other games of that genres. It would like to have more polish, and it feels like a lot more content was originally planned. Right now, it feels like you either have to grind a lot or find loopholes to progress. Still, the graphics and style are awesome!
(Picking the shotgun at the start definitely was a mistake, the revolver is the best)