Good work on getting it submitted! But it really needed a lot more work on it.
I managed to beat it, but it really is a bit of a grind to get to the top. Enemies are way too tanky for how slow you shoot and how many there are. You shouldn't have to retreat back down an elevator and trick the AI to slide down the hallway to try again. I was also able to lure all the enemies down using the spawn point side of the building. Having enemies only become enabled when you reach their floor would be a good way to make sure they don't all coagulate on one level and make it almost impossible to get through without a tedious series of kiting underneath them.
Even during their death animation, they behave the same until they completely disappear. It'd be good to disable all their behaviors during while theyre dying, as it's quite frustrating that they eat your valuable bullets (in terms of time) for no gain. That, and they can also still damage you when you've already killed them.
I still had a bit of fun with this trying to play around with what I could break though