I'm teaching a creative writing after-school class, and while I have projects and some activities from previous lessons/camps, I don't have very many games. While it won't be a game-based class, I still think it would be fun for students to play storytelling-based games.

These are the few I've come up with:
- Mafia (I don't think I'll have enough students for this, unfortunately)
- Madlibs (more of an activity, I guess, but quite fun)
- Silly Stories (exchanging the story after each line, also not really a game, though)
- something with Story Cubes
- "Foreign Movie Dubbing" (from "Whose Line is It Anyway?" - 2 students act and speak in gibberish, while 2 students "translate" what they're saying, and a story unfolds)
- a Balderdash-style game where you show the students a picture, they write a sentence or two about what happened to create that strange situation, then you present all the stories (including the true one) and students guess which is true, getting points if others choose their made-up story
- a book summary version of Cards Against Humanity (i.e. A(n) __________ Goes on an Adventure in _________)
[does smth like this already exist? Otherwise I can make my own]

Any other ideas / suggestions?

How's about a 'Choose Your Own Adventure' kind of thing? Show the kids an example story and then get them making their own?

I also remember seeing some materials somewhere here for a Dungeons & Dragons type activity, ought to fit the storytelling theme pretty well?

Oh yes, I forgot to include that in my list. I've done a "Choose Your Own Adventure" simple comic project before. Could totally do that again - here's the link for anyone who might want to try it.
https://www.youtube.com/watch?v=A9Er7kmcPcI (a vid of how to make it; it unfolds for each choice)

Dungeons and Dragons might be fun, but idk how regularly these students will come, and as far as I know, D&D requires all members of a party to play. I also have no experience playing / being a dungeon master, so I don't know how  well I could direct such an activity.

I took an idea another poster made (I don't remember who) and made a PPT template from it.

It is a game where students make a ghost story one sentence at a time. It is meant to practice the past tense.

It's a pretty low thrills ppt, but you'll get the idea.

Another awesome resource is Rory's Story Cubes.

Story Cubes are essentially a set of 9 dice with different pictures on them. You roll them, and then tell a story based on the pictures that come up. There are many different sets.
https://www.youtube.com/watch?v=L4w41tUfUE4

Gloom is a card game you could play if you have some high-level students. I mean VERY high-level.
https://www.youtube.com/watch?v=Ld9kIHghpRc