Samurai Shodown VI, known as Samurai Spirits: Tale of the World's Greatest Swordsman (サムライスピリッツ 天下一剣客伝 Samurai Supirittsu Tenkaichi Kenkakuden) in Japan, is the tenth iteration in the Samurai Shodown series.
The game features new backgrounds with 2D and 3D elements, as well as a returning cast of all 28 characters from Samurai Shodown V Special, 2 sub-boss from "Samurai Shodown V", as well as all 7 characters from Samurai Shodown and Samurai Shodown II that didn't appear in later games, and 4 new characters. It also features a "spirit select" system, which allows players to choose between six different fighting styles based on all previous installments.
Despite normal Samurai Shodown releases and distribution outside of Japan, the game has been released outside of the country on the Atomiswave system sponsored in the United States by Sega. The game was released for the PlayStation 2 in Japan on January 25th, 2006. The American and European home versions were released respectively on March 24th and March 29th, 2009 on the PS2, PSP and Wii as part of the compilation Samurai Shodown Anthology. The PS2 release added even more playable characters, and three more spirit select systems to go along with them. With the PS2 release, virtually every character to have ever appeared in the Neo Geo games including the referee, Kuroko, and the animal characters, are all playable. The Samurai Shodown Anthology version is similar to the PS2 version except that everything is unlocked at the start.
Source: Wikipedia, "Samurai Shodown VI," available under the CC-BY-SA License.