Basically, I'll start. You say if you want to go up or down the stairs and what you find there.
E.g.
Basically, you put if you go up/down the stairs, what level you're on then, and what you find there.
Rules:
1. You cannot leave the building.
2. No elevators.
3. You may only go up/down 1 level at a time.
I'll start.
You go down the stairs to level -1 (The basement).
There, you find a box inside a box inside a box inside of a box that is on fire.