It is nice to see the aesthetic from the 1D-metroidvania fleshed out like this. Is this in the same universe?
The gun pile mechanic is unique and a non-trivial implementation. It's pretty good flavor, especially for these 2D run-and-gun games that usually don't do anything too out there.
Horizontal movement is a bit slow and the enemies are a bit too spongy. If you're trying to emphasize the gun I suppose that is reasonable, but it does feel a little bit strange how you end up with mobility that's better in the vertical axis than horizontal. The vertical level is pretty solid and I think these vertical climbs are the best setup the game has at the moment.
It doesn't seem like there is a penalty for spamming parries. Doing just that seems like it might be the only way to keep the style meter up on bosses. IDK if a time-based chain/style meter mechanic is optimal for how this seems to be more on the methodical side. I guess I'd have to get good to figure that out.
The presentation is insanely polished already in all places. Well done.