Halo 2

Halo 2 is a shooter game. Players primarily experience gameplay from a first-person perspective, with the viewpoint shifting to third-person for vehicle segments. Players use a combination of human and Covenant weaponry and vehicles to progress through the levels. Certain weapons can be dual-wielded, allowing the player to trade accuracy, the use of grenades, and melee attacks for raw firepower.

The player can carry two weapons at a time (or three if dual-wielding, with one weapon remaining holstered), with each weapon having strengths in different combat situations. Most Covenant weapons, for example, overheat if fired continuously and eschew disposable ammo magazines for an internal battery, which cannot be replaced once depleted. Human weapons are less effective at penetrating shields and require reloading ammunition, but cannot overheat due to prolonged fire. Players can hijack enemy vehicles and quickly assume control of them.

Halo 2 takes place in the 26th century. Humanity, under the auspices of the United Nations Space Command or UNSC, have developed faster-than-light slipspace travel and colonized numerous worlds. Human worlds come under attack by a collective of alien races known as the Covenant. Declaring humanity an affront to their gods, the Forerunners, the Covenant begin to obliterate the humans with their superior numbers and technology.

After the human planet Reach is destroyed, a single ship, The Pillar of Autumn, follows protocol and initiates a random slipspace jump to lead the Covenant away from Earth. The crew discovers a Forerunner ringworld called Halo. Though the Covenant believe Halo's activation will lead to divine salvation, the humans discover that the rings are actually weapons of last resort, built by the Forerunners to contain a terrifying parasite called the Flood. The human supersoldier Master Chief Petty Officer John-117 and his AI companion Cortana learn from Halo's AI monitor, 343 Guilty Spark, that activation of the Halos will destroy all sentient life in the galaxy to prevent the Flood's spread.

Halo had not been planned as a trilogy, but its critical and commercial success —selling more than five million copies in three years—made a sequel expected. Xbox general manager J Allard confirmed Halo 2 was in production at Electronic Entertainment Expo 2002, with a planned release in time for Holiday 2003.

Many at Bungie wanted to make a sequel, building on cut ideas from Halo with a more ambitious follow-up. The added publisher support for a sequel allowed greater leeway and the ability to return to more ambitious ideas lost during the development of Halo. Not satisfied with merely restoring cut content, designer Jaime Griesemer recalled that the team "tripled everything", rebuilding the game engine, changing the physics engine, and prototyping a system for stencil shadow volumes. The development suffered from a lack of clear leadership.

Halo 2 received acclaim. On review aggregate site Metacritic, the Xbox version has an overall score of 95 out of 100. Critics judged it a worthy successor to Halo. GameSpot's Greg Kasavin wrote that it successfully built on its predecessor's foundation, and despite shortcomings, its breadth of content made it one of the best action games available.

The audiovisual presentation was praised. Multiplayer especially was noted in being the best on Xbox Live at the time. Game Informer, along with numerous other publications, rated it higher than Halo: Combat Evolved, citing enhanced multiplayer and less repetitive gameplay. Most critics noted that Halo 2 stuck with the formula that made its predecessor successful, and was alternatively praised and faulted for this decision.

Halo 2's release was part of a shift towards blockbuster gaming releases. In 2004, the video game industry was estimated to gross $7.76 billion in the United States, behind the $9.4 billion gross of the domestic box office. Halo 2's success was seen by the press as evidence of a generational shift in entertainment. The CBC's Greg Bolton remarked that prior to Halo 2's splashy release, "the video-game industry hadn't yet found a recognizable public face, a universally acclaimed megastar." The Ringer called Halo 2 "the birth of the video game as we know it today: a mass shared experience," and credited it with birthing modern multiplayer infrastructure and popularizing American esports.

Halo 2's matchmaking technology was one of the turning points in the gaming industry during the 2000s, setting a new standard for other games. G4's Sterling McGarvey wrote that "Bungie's sequel was a shot in the arm for Xbox Live subscriptions and previewed many of the features that would set the standard for Microsoft's online service on the next machine". Critics credited it with bringing online multiplayer to the console masses, and as serving as Xbox Live's killer app. The Province's Paul Chapman wrote that games like Call of Duty: Modern Warfare 2 would not be enjoyable if not for the ground Halo 2 broke.