Novel Games Poptropica Can I Write A Final Fantecy Novel Like The Games?

Can i write a final fantecy novel like the games? - novel games poptropica

I am a big fan of fantecy final and I realize I have not a true story ... I thought to me is based on a play, to write, but if reason is that I am not entitled to since my ilde not .... As I do not need to write a story, it legally?