Cradle is the strange planet on which Spiral Knights is set.
Cradle has an elaborate machinery inside it, called the Clockworks. It is organized into gates that provide access to different sections, levels found in each tier and the subtowns at the beginning of lower tiers.
The Arcade features four active gates in rotation. Gate themes are randomly generated. However, the random generation prevents two themes from occupying the same tier. Interacting with a gate console opens the mission UI with the appropriate gate selected.