The Testing Facility Moon orbited the planet Dobbo. Lunar City was the only place there. Ratchet and Giant Clank had to travel up to Lunar City to fight the Thugs-4-Less Leader to prove to The Mathematician that they were worthy to enter the MegaCorp Games. Because of its size, Lunar City had a low gravity field, which allowed Giant Clank to jump much higher than on either planets Quartu or Veldin in the original Ratchet & Clank.