Zero simply added new songs and new steps. If a game is not noted in this section, then that game simply introduced new songs with few noteworthy changes. Although it was developed by a different developer and only has four arrow panels, In the Groove 2 was originally marketed as a Pump it Up game. Pump It Up Zero was released in the arcade in January 2006 before releasing on the PSP in October of the following year. Zero contained a brand new interface, now featuring previews of background videos and the ability for two players to play on separate difficulties. Zero also contained the Easy Station, a mode containing a modified interface and a selection of easy songs. The Mission Station contained sets of songs played with specific conditions that must be met when they are played – such as getting a specific amount of a judgment for instance. Zero also introduced the "Another" step chart difficulty. Another Step songs are not entirely new songs. Rather, they are songs with steps which differ from their original counterparts drastically with some being very experimental in nature. Another Step songs are not given a specific category and are listed with the regular charts for each song. Generally the difficulty of Another charts range from easy to extremely hard, with some songs being impossible to complete without a second player. This has remained a standard feature in later games. Pump It Up New Xenesis, or NX, was released in December 2006 with new tracks and a mode with nonstop remixes. The channel arrangement on NX was altered, now featuring a default channel containing all 29 new Arcade Station songs. NX is World Tour was a new series of missions for Mission mode named after capital cities of various nations throughout the world as well as after the developers of NX at Nexcade. It consists of a group of 64 missions of three songs each, all with unique step charts containing various challenges such as passing a song, or completing a song with specific conditions or goals to accomplish. The Remix Station from Zero had been changed to the Special Zone: an area containing nonstop remixes, long versions of songs, and Another mode songs. All of Pump it Up Zeros Another songs have also been moved to the Special Zone. Most of the unlocks, however, depend on playing through World Tour mode. In