Sonic Storybook Series

The Sonic Storybook series is a collection of Sonic games exclusive for the Wii, in which Sonic travels into the world of a storybook to stop a great evil that potentially threatens both his world and theirs, meeting alternate versions of his friends and enemies in the process.

Games in the series
So far, only two games have been released:
 * Sonic and the Secret Rings: With the help of a young genie named Shahra, Sonic must travel into the Arabian Nights and prevent the Erazor Djinn, an evil version of the genie in Aladdin and the Magic Lamp, from destroying the world in the book and entering his own.
 * Sonic and the Black Knight: With the aid of Merlina, granddaughter of the famous Merlin, Sonic must learn swordplay to defeat a corrupted King Arthur and save Camelot.
 * A third title was announced on June 29, 2011. This game will complete the Sonic Storybook trilogy.

Trivia

 * According to SEGA's Facebook, there is going to be another storybook game following up after Sonic and the Black Knight. Some of the choices are: Greek Mythology and Legends, Western/Cowboy, Sci-Fi, and Horror. There are official polls that you are allowed to vote on out of some of these choices.
 * SEGA of Mexico said that the Storybook series would be a trilogy.
 * In Sonic Generations, Sonic remarks to Tails that their current situation is "no stranger than rescuing genies in magic books," indicating that, despite its spin-off status, the Storybook series is canonical (At least, Secret Rings).
 * It is never actually explained what method Sonic uses to returns to his home world after defeating the evil in either storybook game. Though, it can be assumed he left the same way he came, with the magic of Shahra (in Secret Rings) and the summoning spell of Merlina (in Black Knight).
 * On the back of both boxarts, Sonic is in the same pose.
 * Tails and Knuckles are the only characters besides Sonic that appear in all of the Storybook Series games so far, as altenate forms.