Halo: Combat Evolved

Halo: Combat Evolved is a first-person shooter video game developed by Bungie and published by Microsoft Game Studios. It was released as a launch title for Microsoft's Xbox video game console on November 15, 2001. Microsoft released versions of the game for Windows and Mac OS X in 2003. The game was later released as a downloadable Xbox Original for the Xbox 360. Halo is set in the twenty-sixth century, with the player assuming the role of the Master Chief, a cybernetically enhanced supersoldier. The Chief is accompanied by Cortana, an artificial intelligence. Players battle various aliens as they attempt to uncover the secrets of the eponymous Halo, a ring-shaped artificial world.

Bungie began the development of what would eventually become Halo in 1997. Initially, the game was a real-time strategy game that morphed into a third-person shooter before becoming a first-person shooter. During development, Microsoft acquired Bungie and turned the game into a launch title for its new video game console, the Xbox.

Halo was a critical and commercial success, and has been praised as one of the greatest video games of all time. The game's popularity led to labels such as "Halo clone" and "Halo killer", applied to games either similar to or anticipated to be better than it. Its sequel, Halo 2, was released for the original Xbox in 2004, and the game spawned a multi-billion-dollar multimedia franchise that incorporates games, books, toys, and films.

Setting
Halo: Combat Evolved takes place in a 26th-century science fiction setting. Faster-than-light travel called slipspace allows the human race to colonize planets other than Earth. The planet Reach serves as an interstellar hub of scientific and military activity. The United Nations Space Command (UNSC) develops a secret program to create augmented supersoldiers known as Spartans. More than twenty years before the beginning of the game, a technologically advanced collective of alien races called the Covenant begins a holy war against humanity, declaring them an affront to their gods. Humanity's military experiences a series of crushing defeats; although the Spartans are effective against the Covenant, they are too few in number to turn the tide. In 2552, Covenant forces attack Reach and destroy the colony. The starship Pillar of Autumn escapes the planet with the Spartan Master Chief Petty Officer John-117 on board. The ship initiates a jump to slipspace, hoping to lead the enemy away from Earth.

Plot
The game begins as Pillar of Autumn exits slipspace and its crew discovers a large ringworld structure of unknown origin. The Covenant pursues the Autumn and attacks. With the ship heavily damaged, the Autumn 's captain, Jacob Keyes, entrusts the ship's artificial intelligence (AI) known as Cortana to Master Chief in order to prevent the Covenant from discovering the location of Earth. Keyes orders the crew to abandon ship and pilots the Autumn to a crash-landing on the ringworld.

On the ring's surface, Master Chief and Cortana rescue other survivors and help organize a counter-offensive. Learning that Keyes has been captured by the Covenant, Master Chief and a small contingent of soldiers rescue him from the Covenant cruiser Truth and Reconciliation. Keyes reveals that the Covenant call the ringworld "Halo" and that they believe it to be a weapon. Intent on stopping the Covenant from using Halo, Keyes searches for a potential weapons cache, while Master Chief and Cortana mount an assault on the ringworld's control room. Cortana enters Halo's computer systems; what she learns has her immediately send Master Chief to find and stop Keyes from continuing his search.

Searching for the captain, Master Chief encounters a new enemy, the parasitic Flood. The release of the Flood prompts Halo's caretaker, the AI 343 Guilty Spark, to enlist Master Chief's help in activating Halo's defenses. After Master Chief retrieves the ring's activation index, 343 Guilty Spark transports him back to Halo's control room. Cortana intervenes before Master Chief can activate the ring; she has discovered the purpose of the installation is to destroy all sentient life in the galaxy, starving the Flood of potential hosts. When Cortana refuses to surrender Halo's activation index, 343 Guilty Spark attacks her and Master Chief.

To stop Halo's activation, Master Chief and Cortana decide to destroy the installation. Needing Keyes' command codes to destroy the Autumn and Halo with it, Master Chief returns to Truth and Reconciliation, only to find that Keyes has been assimilated by the Flood. Retrieving the codes from the captain's remains, Master Chief returns to the Autumn, but 343 Guilty Spark halts the self-destruct sequence. Master Chief and Cortana manually destabilize the ship's reactors as an alternative, narrowly escaping the ensuing detonation in one of the Autumn's fighters, while the majority of the remaining Covenant, UNSC forces, and infected Flood are destroyed along with the Halo installation. Cortana justifies their sacrifices and believes their work to be finished, but the Master Chief states that they are only getting started. 343 Guilty Spark is shown to have survived Halo's destruction in a post-credits scene.