United Nations Space Command

The Halo video game and media franchise takes place in a science fiction universe, where there are four major factions players encounter or control. Halo's story has 26th century humanity, led by the United Nations Space Command (UNSC), caught in a war with an alien coalition known as the Covenant. In the 2001 video game Halo: Combat Evolved, the UNSC ship Pillar of Autumn discovers a mysterious ringworld known as "Halo". The massive installation was built by an enigmatic race known as the Forerunners, who have long since disappeared; the Covenant worship the Forerunner as gods. During the course of the game, players discover that the Halos were built as a weapon of last resort against the Flood, an extragalactic parasite which is driven to consume all sentient life. The Forerunners were forced to activate the Halo network, killing themselves and any potential Flood hosts, in an effort to starve the Flood to death. The Covenant leadership discovered Humans could interact with Forerunner technology, and decide to destroy humanity in order to suppress this fact. The Flood, meanwhile, escape the confines of Halo and threaten to spread across the galaxy again.

A large portion of the series' success lies in the creation of a believable world, and Bungie reinforced the fictional factions the player interacts via a lengthy design process with the release of each game. The overall design of each faction was slowly developed before the release of the first game in the series, Halo: Combat Evolved, and continually refined in the later games' development.

Reception of Halo's factions has generally been positive. The Covenant were praised by reviewers as exciting and challenging enemies. Characters, weapons and vehicles of all the factions have been released as toys or promotional materials.

Early in the video game Halo: Combat Evolved's development, Bungie environmental artist Paul Russel solidified the concept of three "schools" of Halo architecture for the main factions in the game—the humans of the United Nations Space Command (UNSC), the alien alliance of the Covenant, and the Forerunner structures on which most of the game takes place. For future humanity, the artists and developers settled on a functional, industrial look. Art Director Marcus Lehto said that the artists examined current technology trends and tried to extrapolate what future technology would look like. Designs were molded by the desire for building a realized and distinctive feel for the human ships and buildings, but also to make the areas fun to play in. For example, the design team wanted a cramped, claustrophobic feel for the human ship levels in Combat Evolved.Ron Cobb's work on Aliens informed some of the design for a "lived in" appearance. In comparison to the visions of dystopia common in many other science fiction works, the cities and buildings of Earth which were first shown in Halo 2 were clean and functional, with parks and attractive structures. Character design for the UNSC was more straightforward, with uniforms based on existing military outfits, ranks, and insignia. All aspects of the game were designed to feel believable and cultivate suspension of disbelief.

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