The concept
A community-controlled game (CCG), is any video game featuring a single avatar that is controlled by more than one person. As the definition of a CCG refers to the way a game is played, rather than aspects of the game itself. Wikipedia
The game is played with the storyteller or gm or op writing the narrative of the game and giving players choises to vote for. The storyteller can also give players the chance to do write-ins as a choice to vote for. If not otherwise stated voting is done by upvoting the preferred option. After appropriate time the winning option advances the narrative of the game. The game is moderated by the storyteller.
Community involment greatly enhances the experience so players are encouraged to take active part in shaping the world of the game. Illustrators, DJ:s and people doing amacing write-ins are allways welcomed.
The point
The goal is to have fun. These types of games are also a way of aspiring writers to test their ideas and find interesting consepts to work on.