This is a game that I like to play with my intermediate-advanced students in high school.
(1) I take them to storytimed.com.
(2) I scroll to a story that I pre-selected during my lesson planning (one that I think has the most potential for fun writing).
(3) I have the students continue the selected story on pieces of paper (for 7 minutes, as per the guidelines on the website).
(4) Together, the class votes for the best story (students cannot vote for their own story).
(5) Finally, with my account, I upload the best story to the website. If students feel their story would make a good addition anyway, despite having lost the "election," they can just go ahead and upload the story on their own time. The website is very user-friendly in my opinion.
You can sign up for a free account, and the registration process is quick and easy. I just think it's a great teaching tool, and I wanted to share it with y'all.
Best of luck,
T