Wow, what an incredibly well polished game. To have made this in one month is a moonshot achievement ;)
Where do I even start with my thoughts. Everything is top notch. Visuals are simple but perfect for the feel of the game. The little characters have so much personality. The screen shake makes such a big difference to the feel of the shots. The colors are striking and memorable. The chromatic aberrations add to the aesthetic and give it a very interesting look.
The sound design is fantastic. The music is perfectly fitting for the feel of the game, the sound effects are heavy and feel very impactful. The character speech sounds are very nicely done. You could have totally skipped out on it but your attention to detail clearly shows.
The presentation was extremely polished and professional. The menus have their own look and feel to match the aesthetic of the game. Everything from the font choice to the hyper stylized look make it stand out and feel unique in a world where menus usually receive the least attention. Incredible job on on that.
The one critique I have is that the left and right guns look and behave the same (at least as far as I played) If they had been different colors, that would have made it easier to mentally associate with the left and right hands. As it is now, once I start moving and the character starts turning, which gun is left or right is pretty much guesswork. Would have also been interesting to explore what happens when the guns are different on each hand. Would have added a new dynamic where certain situations preferred one gun over the other and you would have to position yourself for the best advantage.
Overall, an incredible experience, and a very viable commercial product. If you fleshed this game out and added more to it (more guns, more characters, more playstyles, more replayability) it could become a very very popular mainstream game. I really hope you continue to work on this post jam. The sky is the limit! :)