Sometimes, you may come across a passage in your wall. Where does it go? What's inside? Take your key with you, or you may never see your world again. Bring food too, because it doesn't like to see you on an empty stomach.
Sometimes, you may find a path. Where does it go? What lies just over the rim? Take a look for yourself, and hold onto that key. The food as well. Don't forget, because it's hungry, and is getting hungrier by the minute. Don't waste time. Be swift.
Sometimes, you may find a hollow log with a ladder leading underground. Where does it go? What is beneath the surface? At this point, you should ask yourself what that rumbling feeling is. It's getting hungrier. Descend the ladder with your key and your food. Pray to your deity that you brought the right food for it, or else you can kiss your life goodbye.
Sometimes, you may find a blank wall. Did you forget your chalk? That's too bad. Maybe you can try again in your next life, because it's starving now, and it's right behind you.
If you were wise enough to bring your chalk, do not draw a door on the wall. Do not be such a fool. Rather, draw a circle around you with a handle shape in the center. Do not draw a lock. This will only trap you. Touch your key to the outermost edge of the circle, and descend into the resulting passage.
Sometimes, you may discover a corpse. Who is it? Why is it rumbling? You've found it, and it's craving a meal. Did you bring the right food? You didn't, did you? That's okay, because it's just as happy devouring your still-beating heart as it is eating a fine meal.
Sometimes, you may satisfy it with your food. Why is it standing? What is it saying? The words it speaks to you may never be repeated to another mortal, as the mere mentioning of the words would corrupt them to the point of no return. You are no longer a mortal. The only thing it asks of you is that you leave the key where another may find it.
Sometimes, you may find a key. And it begins again.