Play it alone or with other people.

I usually play it with movie actors, but you can use any characters, fictional or otherwise.

First person picks two characters/actors who never interacted. Let's take Dolly Parton and Tim Curry. Second person/team has to come up with a story involving the two. They can be any age, so it can be 60 year old Dolly mentoring a young Tim, or old Tim being cared for by Dolly aged 30.