Playfic is a site I've covered in the past that is ideal for Creative Writing. This is an innovative site that lets users create text adventure/choose your own adventure games (i.e. Zork). It uses a programming language called Inform 7, that is rather user-friendly and a user can have created a game in minutes. This is a great way to spark creativity and help students practice their Writing skills.
I highly recommend checking out Playfic by clicking here!!!