The first "Sonic" game for the Wii, "Sonic and the Secret Rings" (2007), takes place in the world of "Arabian Nights" and was released instead of a port of "Sonic '06". Citing lengthy development times, Sega switched plans and conceived a game that would use the motion detection of the Wii Remote. Sega released a sequel, "Sonic and the Black Knight", set in the world of King Arthur, in 2009. "Secret Rings" and "Black Night" form what is known as the "Sonic Storybook" sub-series. A "Sonic Riders" sequel, ' (2008), was developed for the Wii and PlayStation 2. Dimps returned to the "Sonic" series with "Sonic Rush Adventure", a sequel to "Sonic Rush", in 2007, while BioWare developed the first "Sonic" RPG"," ' (2008), also for the DS. Backbone Entertainment developed two "Sonic" games exclusive to the PlayStation Portable, "Sonic Rivals" (2006) and "Sonic Rivals 2" (2007).