You choose a numeral, type it, then the next person types a word to make a story

[3tbear]

I will start by saying the letter b and will pick a word that starts with the letter b to start the story:

Before

then someone else might put the letter t and then put a word that starts with that letter:

time

(Now someone else pick a letter and make it into a word for the story to make sense).

So far our story starts out (Before time)...

[Teah]

Before time (R) RAN

[Corganiacs]

before time ran *A* AWAY

[Teah]

Before time ran away *O* ON

[flash3992]

"N" 9/11