Halo 4 is a shooter game in which players predominantly experience gameplay from a first-person perspective; the game perspective switches to third-person when using certain weapons, abilities and vehicles. The player's head-up display (HUD) shows real-time information on the player character's armor system, such as shield status, information on current weapons and abilities, and waypoints for goals and objectives. The HUD also has a motion tracker that detects allies, enemies, and vehicles within a certain radius of the player. The game sees the return of the alien species who were formerly members of the Covenant as foes, and introduces a new type of enemy called the Prometheans, which are Forerunner A. I constructs. There are three types of Prometheans: Knights serve as leaders of the group and are considered the deadliest of the Promethean forces; Crawlers are a weaker class that often attack in packs; and Watchers offer support and have the ability to shield or revive Promethean allies.