Sonic and the Black Knight (ソニックと暗黒の騎士 Sonikku to Ankoku no Kishi) is a title within the Sonic the Hedgehog series, released exclusively on Wii as the second entry in the Sonic Storybook series, following on from Sonic and the Secret Rings. The game is directed by Tetsu Katano, who was the lead programmer of the Sonic Adventure titles and Sonic Heroes. Set in the world of King Arthur, the game combines Sonic's trademark speed with a new swordfighting system, utilizing of the Wii Remote's motion-sensing functionality. Note that series villain Eggman is absent here, making this the only Sonic game that he does not appear in.
Sonic and the Black Knight was de-listed in 2010, following on from Sega's decision to remove all Sonic titles with average Metacritic scores from retail stores in order to increase the value of the brand after positive reviews for Sonic 4 and Sonic Colors.
Gameplay for Sonic and the Black Knight differs from traditional games in the Sonic series by mixing in the new element of swordplay with the traditional Sonic platforming and speed. Swordplay is implemented through the Wii Remote. Gameplay is more similar to Sonic Unleashed than Sonic and the Secret Rings; Sonic's movement is controlled with the analog stick as he is on a set course, and gameplay is mainly 3D.
Source: Wikipedia, "Sonic and the Black Knight," available under the CC-BY-SA License.