One Word Story: Create a story, one word at a time.

Alphabet Story: Create a story with sentences that start with consecutive letters of the alphabet.

Questions Only: Have a conversation, using only questions.

Fortunately / Unfortunately:  Construct a story, alternating between lines starting with "Fortunately" and "Unfortunately."

Party Planning: Collaborate to plan a party by "Yes, and-ing" every idea with more silly and creative ideas.

Sentence at a Time Story: Build a story by taking turns offering the next sentence. (From Arastoo!)