This is really well done! It's basically a nice Enter the Gungeon done in just 7 days! The controls and gameplay are exactly that, which I am not going to complain. The graphics (especially) the biscuit player character and the weapons are really well made! I also think that you've got the time and effort to make 9 different weapons and a boss, which is really impressive. The heat meter is a nice addition as well, where, although it doesn't make that much of a difference, it's cool to be at the edge of dying yet being super powerful. Got that red tearstone ring vibe to that, and I really like that.
For some minor criticisms, I think the room layout is a bit detrimental to the game, as with the amount of enemy projectile spam, the narrow corridors, which the current map mainly consists of, make the game really frustrating to play, as it will be just flooded with bullets, making it a waiting game. It also makes the melee weapons virtually useless. I think having larger and more spacious rooms would be far better as an alternative. Another thing is that the collision is a bit strange, where it felt like bullets are not connecting reliably. The upper part of the wall also had a collision for some reason.
Anyway, I think this is still a very nice entry! Well done!