You had made a mistake. Just one wrong line of code, and your work had blown up in your face. When you awaken, it's to darkness.

Dark, Darker, and yet Darker still.

Before you could panic, you could sense a presence. You turn to find a rather curious looking monster there.

"Greetings, traveler. I am WD Gaster, Royal Scientist of the Underground. It is a pleasure to make your acquaintance, though I must admit, it is not often that I receive visitors in this realm."