Clone trooper film series and in the "Star Wars" expanded universe media, a number of specialized trooper units are seen, including elite special forces units such as the 'Advanced Reconnaissance Commandos' (ARC troopers), and Null ARCs, who usually work alone. All clone commandos and ARCs were trained by Mandalorian mercenaries; the elite Clone Troopers are known as Shadow Troopers. The style and color of a clone troopers armor often varies depending on their rank, specialization, unit, or environment, for example, the clone troopers on Kashyyyk wear camouflage green scout-style armour whereas the 501st legion wears standard white armor with blue accents. Another
Star Wars: Battlefront II (2005 video game) to the four standard classes, each faction has two unique classes which unlock by scoring a predetermined number of points. For the Rebellion faction, the Bothan Spy and the Wookiee; for the Empire, The Officer and The Dark Trooper; for the Republic, the Commander and the Jet Trooper; and for the CIS, the Magnaguard and the Droideka. "Battlefront II" also features heroes - a special class that allows the player to control iconic characters from the "Star Wars" universe. Heroes serve as a bonus to players, and are unlocked by meeting certain criteria, such as earning a certain number of