I went upstairs because I thought it might cause some mutations. You know, like when you go swimming in the pool near the reactor or camp out at the toxic waste dump... Anyone? No?
As you might expect, the place was packed with super-humans. There were guys who could bend time and space just with their brains. At least, that's one possible explanation for some of their claims. Some declared they possessed an intelligence vastly superior to all other lifeforms. While many offered undeniable proof of their intellectual mastery, it appears that their attempts at Global Domination have been derailed by technical glitches. Some blathered on at length about how they would have gotten away with it, too, if it hadn't been for Sonar and those darn kids. (I don't know what Scooby snacks had to do with it...)
All I got was a tail. I don't mean that I got a cool, useful, prehensile tail. It's more of a rat-like thing. I wouldn't mind so much except for the fact that it likes to tap me on one shoulder and then whip to the other side before I can turn around. It also likes to tickle the inside of my ears. I hate that.
The bottom line is that there is no good reason to go upstairs. All the really good mutations are already taken.