The Blue Cyclone, often shortened to simply the Cyclone, is a vessel that appears in Sonic Chronicles: The Dark Brotherhood. It is an interdimensional spacecraft constructed by Tails and Dr. Eggman for traveling through the Twilight Cage. While docked at a colony, it also serves as a stronghold, replenishing the player's characters' HP and PP and allowing the player to reselect their party members.
The Blue Cyclone serves as the party's base of operations throughout the second part of The Dark Brotherhood. The vessel is robustly built, surviving a crash-landing on the Kron Colony, an energy-leeching on the N'rrgal Colony, tractor-beam impounding on the Zoah Colony, and a full-scale space battle around the Nocturne.
After Imperator Ix opened a wormhole to the Twilight Cage using the Master Emerald, Sonic's team planed to follow the megalomaniacal echidna inside to thwart his plans of global conquest. Tails and Dr. Eggman then had the idea of building the Blue Cyclone as a means of pursuing Ix into the Twilight Cage. As such, Sonic and Shade explored Metropolis Ground Zero for the necessary components while Eggman and Tails remained instead within the doctor's weapons lab to assemble the vessel.
Finishing the Blue Cyclone, everyone except Eggman, boarded it and entered the Twilight Cage. Upon entering however, the dimensional interference caused the Blue Cyclone to lose power, forcing them to crash on the Kron Colony. After it was made operational again, the Blue Cyclone was used by the team to travel between the Twilight Cage's planetoids. Ironically, the Blue Cyclone was finally shot down by one of its own creators, when Eggman backstabs the heroes after their escape from the Twilight Cage.
↑"With the Blue Cyclone damaged by the trip through the wormhole, Sonic and his friends were forced to crash-land on the nearest landmass, a planetoid that is home to a race known as the Kron." - The Story So Far, Chapter 7