This article is about a/an alternate reality/A.R. World (another rider's world) in Kamen Rider Decade.
X-Rider vs. Apollo Geist AR

X-Rider vs Apollo Geist in the World of X-Rider.

The World of X-Rider (Xライダーの世界 Ekkusu Raidā no Sekai) is the version of reality where Kamen Rider X takes place. It is where Apollo Geist and King Dark of Dai-Shocker originally came from.

It is home to an alternate X-Rider who, much like the original Keisuke Jin, killed his world's Apollo Geist. Though he was revived by the Government of Darkness, he required the use of his Perfecter to take the life force out of people to augment his own. RX! Dai-Shocker Attack

This A.R. World was not visited by the Hikari Studio during the Kamen Rider Decade TV series, but they could have visited it off-screen after the conclusion of the Rider War and the events of Kamen Rider × Kamen Rider W & Decade: Movie War 2010. Indeed they have the opportunity to do so as the Hikari Studio is left free to travel the A.R. Worlds as of the end of Movie War 2010.