There are some similarities between them. For example, Riku is a little like Anakin Skywalker. Riku was tricked by Maleficent, willingly opens himself to the darkness, and allows Ansem to possess him. Anakin was tricked by Palpatine, allowed himself to be corrupted by the dark side, and forms an oppresive empire. Star Wars and Kingdom Hearts both have a light versus dark theme.