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. 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.

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.
 * It is possible that there is a single entity corrupting different universes. Possibly an entity resembling Shahra or Merlina, since they both look alike.