Really dope game!! The art is great, love the character and the general aesthetic. The tilesets and backgrounds do get a little repetitive, and it can be hard to tell when you're going in a circle because all the rooms look so similar in such huge zones.
I liked the crafting mechanic. Being able to choose between hp upgrades or heals is a very nice way to reward players for grabbing tickets, although I would maybe suggest the max HP increasing drinks to come with health, because it's a bit of a chore to pump up your HP that high and then spend a bunch of drinks in a row just to have full HP.
The mechanics feel really nice, all of the weapons feel great, jumping and dashing is responsive, it all just works! I really love using the shotgun, it feels powerful and the jumping with it feels fluid.
Dashing I think it could benefit greatly from some sort of visible cooldown, like the guns have, since the distance between jumps feels a bit long (which is understandable, might be too much power to zip rapidly). I think either a meter/timer in the UI or some kind of variation on the character sprite would help the player know exactly when they can dash again.
As far as metroidvanias go, colored doors are probably my least favorite obstacle... I ran into a loooot of red doors and yellow doors and you can't even attempt to bypass them, they're simply a wall. Even something like a phaser lock is a little bit more fun, since it hints to you that there IS a piercing weapon you could find, rather than a yellow keycard.
For an example, I think rather than having just a blue door, have a door that opens when you press a switch on the other side, which you can make by shooting a trick shot arc with the stream gun. Instead of a yellow door, a burst jump obstacle is all you need. Although given how samey the rooms looked, having colors did help a little bit with remembering places to backtrack to.
Game overs were a bit frustating in the early game, especially because some enemies seem to kill you VERY suddenly. I think there may be a discrepancy in me not realizing how low my HP is, because earlier in the game I would increase my health bar with drinks, die without finding a place to save, and then when I respawn I don't really notice anything is different because the health bar never changes size. While it does look very slick and solves the problem of an infinite potential health bar, I feel like it probably would have been better to use a smaller health bar that grows. If you're worried about it overflowing, I'd suggest using stock like Metroid reserve tanks or layered health bars where they change color and start over after depleting.
Figuring out how to do the recoil jump was kind of difficult. It's cool when you get it down, but at first you sort of expect it to work like a double jump. I tried many variations of jumping off the platform on the left and shooting down and dashing to no avail. (Which, good thing that DIDN'T work, otherwise I might never have figured it out)
That and at first I didn't even realize that burst was a separate gun that I had just received, separate from the constant fire lol.
It also feels pretty inconsistent, sometimes I can get really high, sometimes I don't go nearly as high, and I'm still not 100% whether or not the shotgun works more like a double jump or if it's just the burst gun but higher.
The item getting could use some fanfare and important text so it's not mistaken for something less important like a drink ticket. Several times I'd pick something up and not even realize until the room tried to teach me what it was.
Having just beaten the game, was there even a red gun at all?? It wasn't necessary to get to the 'end of current build screen'. I spent WAY too long going in circles looking for it, being completely lost. If there's no red gun I'm actually devastated lol. That'd be mean. I only even attempted the endgame because I had reached the point of exhaustion looking for it.
Also the new game button doesn't work, it starts you back at the initial room with 100 HP, but I started with all my guns.
PHEW ok I know this was a LOT of critique BUT I really actually like this game a LOT and I think it could be the start of something really great if you wanted it to be, the engine is very solid and the mechanics work very well, it's a lot of fun and I hope you iterate on it! Great work!