This goes so hard. Like everyone else said, the juice is off the charts, and the frenetic pace is just perfect!
That said, I did have a few (altogether minor) things that I wish were tweaked just a bit.
The targeting reticle ends up confusing me a bit when playing on m+kb. The fact that the controller reticle that's locked to a specific distance from the player doesn't go away, and is also a bit more visible, really throws me off in the middle of the chaos, and tricks me into thinking my mouse is somewhere it isn't. I think the reticles could pop more in general given how much chaos there is in general, since it's pretty easy to lose track of.
Another issue is the screenshake. While there were a couple times I felt like I died because I misplayed, more often than not I ended up dying a few floors in after firing a shotgun or molotov a couple times in a densely-packed room and then taking two damage from... something, and having no idea what happened. When you're firing high-knockback weapons into dense rooms or exploding barrels, the game becomes almost unreadable for more than enough time for you to die, which doesn't usually feel fair. I ended up frequently avoiding most of the weapons even in favor of the starting pistol just for this reason.
The final thing is room transitions. I would really like it if the doors between rooms were sealed between combats, or maybe if there were an old-school room transition effect where the camera pans over from one room to the next. As-is, if you walk into a new room and fire your shotgun, you can just get blasted backwards into the previous room and the entire room just instantly vanishes - and then odds are, you can't even come back into the room without guaranteed damage since the slimes are still coming towards you even though you can't see them anymore. So you have to camp in the previous room waiting for slimes to come through so you can kill them without taking damage, but at the same time your combo suffers, which can also potentially kill you.
I also got a crash. I'm guessing if you go into the elevator room, pass the check, then *leave* the elevator room (to, for example, pick up a weapon you'd left in a prior room), then return to the elevator room with too low a combo for the check to pass, then it crashes.
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ERROR in action number 1
of Alarm Event for alarm 3 for object oElevator:
Unable to find instance for object index 60
at gml_Object_oElevator_Alarm_3
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gml_Object_oElevator_Alarm_3 (line -1)
That all said, this pretty much checks every box for me, incredible work