Very good game. The feedback from firing the gun is awesome. I love the shop upgrades. The bullet casings on the ground are such a fantastic detail. Since the gun seems like a revolver the way it reloads, it may be cool to "eject" the empty shells once the reload starts rather than each time the gun is fired.
Now for the critiques: the embed size is far too large. I had to zoom out my webpage just to see the edges of the embed.
It's frustrating that the day starts with the gun empty every time and seems like a bug.
The enemies get "stuck" on the player once they start attacking and feels bad trying to get away from them when that happens. Could have them bounce back after attacking, or at the very least slow their movement briefly, so it's not an instadeath when they get to you. Also a cooldown on them dealing damage. It feels weird that they sometimes don't damage you when they bump you, but also when they do "connect" they seem to hit like 20x a second.
Movement speed is WAY too high. They player character felt uncontrollable most of the time. Movespeed as an upgrade would be interesting, but mainly lower movespeed across the board with a smaller map and higher values for scaling the timer I think would make for more dynamic gameplay and better exploration.
PS I think the "heal" shop option is bugged. Didn't seem to take coins.