Guardian Units of the Nation Headquarters, or G.U.N. HQ for short, is the main base of operations for the Guardian Units of the Nation. It is located inside Guardian Mountain and is equipped with all the necessities needed for a military organization, including a briefing room, a recreation room, a gym, a laboratory and a hangar with helicopters and fighter jets for transportation needs.
Main Base of G.U.N.
G.U.N. HQ's laboratory was used by Hope Kintobor to build a Zone teleporter to assist Shadow the Hedgehog in the mission given to him by Commander Abraham Tower; go to the Special Zone and retieve a Chaos Emerald. Although the teleporter didn't take him to the Special Zone, Shadow managed to complete his mission anyway after going across three other zones and destroying the latest Metal Sonic. Upon his arrival, Commander Tower informed him he had a new mission; destroy Dr. Eggman's new Doom Laser, which Shadow did successfully with the help of Rouge the Bat and Sonic the Hedgehog. (SU: #1, #2)
Shadow and Rouge were later sent to the briefing room of G.U.N. HQ about their new mission. They were to find and recruit a rogue Eggman robot that was starting to wear down called E-102 Gamma in order to help him. Shadow requested that he not have the help of Rouge and wanted to complete this mission himself after failing to save Metal Sonic in Blaze's world. Shadow then took off in a GUN helicopter at the same time Eggman dispatched the last of the E-100 Series, E-123 Omega, to find and destroy Gamma. Although Shadow located Gamma first, Omega managed to deal with the hedgehog temporarily and destroyed Gamma, but E-102 managed to upload his free will into Omega before being destroyed, making Omega rebel against the Eggman Empire and join GUN after a talk with Shadow. After Omega was brought back to G.U.N. HQ, Shadow went off to the rec room and began talking Hope and Rouge about how he felt bad about failing to save two living weapons instead of just one. Rouge then teased him an attempt to cheer him up and Hope then gave them the folder for their next mission, using Hope's Zone-Breaching Platform to retrieve a Chaos Emerald from the Special Zone. (SU: #3)
Shadow and Rouge went to the Special Zone where they encountered Feist, the master of the Special Zone. He said that they must earn a Chaos Emerald by completing one of his challenges. Shadow attempted to skip the challenge with Chaos Control, but due to Feist's complete control over the Special Zone, Shadow could not tap into his Chaos energy and he and Rouge were forced to do the challenge, but failed. Shadow, blaming himself for their failure, later engaged E-123 Omega in a sparring match as G.U.N. HQ's gym, with Omega taking note of Shadow's agitation. Omega told him not to let his failure concern him, for he would accompany then next time and blast Fiest, causing Shadow to get angry and throw Omega to the floor, leaving the robot in confusion. After Hope reassured Shadow that he didn't fail and only better prepared himself for his next confrontation with Feist, Shadow returned to G.U.N. HQ's lab as part of the newly formed Team Dark. They managed to retrieve the emerald this time, and recieved congratulations from eachother along with Hope and Commander Tower, before giving their superior the emerald. (SU: #4)
- Briefing Room: A moderately large room with many chairs for seating arrangements and a projector, making the room's appearance similar to that of inside a cinema. This room is used to brief agents on their next mission with pictures to help identify their targets.
- Gymnasium: The gym is an area of the base where G.U.N. agents go to either use the exercise equipment, or practice their fighting techniques in the yellow circle.
- Hangar: A large airfield with plenty of helicopters and fighters jets to transport GUN troops and agents to their chosen destination.
- Level Ten Workshop: The Level Ten Workshop is a high-tech lab used by mechanic Hope Kintobor. Hope used this room to make her Flame Shield and Zone-Breaching Platform to assist in Shadow's mission to the Special Zone. It's possible this is her private work space.
- Recreation Room: The rec room is an area of the base where the agents of GUN go to either relax on the sofa, get a quick drink or snack from the machines, or play a little table tennis, pocket billiards (pool) or darts with another agent.
- In the game Sonic Chronicles: The Dark Brotherhood, GUN headquarters was revealed to be in the game universe's capital city of the United Federation, Central City, instead of in Guardian Mountain.