Lets play an game that based off from ROBLOX Doors by LSplash.

You are in the elevator waiting for the elevator to open, Once it opens you'll greeted to lobby which you'll need an key to open the Door 1, After you open Door 1. You'll be greeted with various rooms with doors that can change it's number once you progress through, Reaching door 50, You'll be greeted the library and The Figure, Reaching door 100, You'll be greeted with basement and same figure.

The Entites lies ahead to rooms.