A Freeform Storytelling Roleplay is a unique kind of text-based roleplay, in which players are to cooperate writing a story, with very few to no limitations. Unlike most other kinds of roleplays, in Freeform Storytelling Roleplays you are fully permitted to use the characters of other players and alter their plots - with exceptions, though.
The Avataria-series is a series of Freeform Storytelling Roleplays.