Halo 2 is an award winning first-person shooter video game made by Bungie Studios and published by Microsoft for its own Xbox console. It was released all over the world on November 9, 2004. It is the second game in the Halo series the first being Halo: Combat Evolved and the third being Halo 3. A Windows Vista version of the game was released in 2007. 

The game's story is based around a future war between a fictional confederation of alien races known as the Covenant and the human race. The player takes the role of Master Chief, a genetically enhanced super soldier who fights for mankind. The player is helped in their fight against the Covenant by human marines. The game had many features that were not in the original Halo such as extra vehicles, weapons and a greatly improved multiplayer mode, including the ability to play over Xbox Live. 

Halo 2 was the most popular Xbox Live game on its release. It held that title until the release of Gears of War nearly two years later. By June 20, 2006 over 500 million games of Halo 2 had been played over Xbox Live. It was, and still is, the best selling Xbox game of all time with over 8 million copies sold worldwide. It broke sales records in the US, many of which were only broken by its sequel Halo 3 in 2007. The Windows Vista version in 2007 was less successful as the fact it was released 3 years after the Xbox version gained many negative reviews.

Gameplay 
Halo 2 is a science fiction first-person shooter based mostly on foot but with vehicle combat sections. Halo 2 has many features that were not in the original Halo. In Halo 2 players have the option to use two weapons at once, called dual wielding. This allows the player much more firepower but does not allow the throwing of grenades. The player can hold up to two weapons at once or three when dual wielding. Weapons range from normal human weapons such as pistols and shotguns up to heavy weapons like rocket launchers and sniper rifles. The player can also carry alien weapons like plasma rifles and needlers.

Story Mode 
The story mode continues the story started in Halo: Combat Evolved. There are nine levels in the story, split between controlling Master Chief and the alien Arbiter. There are four difficulties to the campaign easy, standard, heroic and legendary Completing them unlocks extras such as different dialogue in certain sections of the game, and extra weapons in split-screen multiplayer. There are various 'skulls' at hidden parts of the levels, as in Halo 3. These skulls unlock helpful and or strange differences in the levels such as confetti and balloons appearing when the player scores a head shot. The story can be played two player on the same console but not over Xbox Live.

Multiplayer 
Halo 2 allows up to four players to play on the same console or up to sixteen over Xbox Live. The game was influential in changing the way games played over the internet. Before in most online multiplayer games, one player was the host who used their own connection for the game and chose the settings, game type etc. In Halo 2, and most games since, players choose a type of game they want to play and the game matches them with players of their own ability on a randomly chosen map.

Some weapons and vehicles available in the story mode were not available in multiplayer as they would be too powerful and 'unbalance' the game.

Story 
The game is set in the same fictional world as the rest of the Halo series. Much of the game takes place in the future year 2552, over 500 years from now. In the story line humans have developed faster than light travel, and now live on many planets  and moons of the Solar System. On humanity's first try to build a settlement on a planet around another star they met the alien Covenant. The Covenant declared religious war on humanity. At the start of Halo 2 humans are losing the war and the Covenant have just discovered Earth. 

The Halo of the game's title is the name of a series of planets 'built' by a mysterious race called the Forerunners a long time before the game. The Halo's are the last defense against another alien race known as the Flood. The Flood want to use every living thing in the galaxy for food. The Halo's are actually giant super weapons, that when activated kill all life in the galaxy. This is the only way to stop the Flood, to starve them by killing all their food. The Covenant are not aware of this and are attempting to fire Halos as part of a false religious prophecy. In the first Halo game, Halo: Combat Evolved, the humans and Master Chief manage  to stop the Covenant from firing one of the Halos. They also destroy one of them in the process. Just before Halo 2 begins the covenant discover another Halo that can only be got through a portal found near Earth.

Plot 
The game opens with the torture of an alien, the leader of the Elites. He is being tortured by the covenant because he failed to stop Master Chief destroying the first Halo in the original game. The Elite commander is branded by the leader of the Brutes, another part of the Covenant. The player then takes control of Master Chief, on board a spacecraft orbiting the Earth when the massive Covenant fleet arrives. The Covenant have come to take the portal that will allow them to get to the new Halo so they can fire it. The Covenant board the ship the player is aboard, and attempt to plant bombs to disable it and the other ships in the human fleet. The player must fight through Covenant forces to disable the bombs. Once this is complete the human ship heads off, following the Covenant flagship that just flew past. Meanwhile, in the cutscene we see the former elite commander being made into a religious warrior known as the Arbiter to make up for his failure to stop Master Chief in the original Halo. 

In another cutscene a human ship with Master Chief,Johnson and Cortana aboard follows the covenant ship through the portal to the new Halo. The player must now take control of Chief as he battles to stop the Covenant from firing the ring. Eventually the player kills the Prophet of Regret, a Covenant leader, and stops the Halo from being fired. Unfortunately before the player can recover the Index, the control for firing the Halo, they are captured by the leader of the Flood, known as the Gravemind. In a cutscene we see the new Arbiter sent down to the Halo to recover the Index before Chief can destroy it. When he arrives though, he and his followers are betrayed and their former allies begin to attack. Here the player must control Arbiter and his followers as they attempt to escape the betrayal and ambush. The arbiter is eventually also captured by the Gravemind and meets up with Master Chief. The two of them break free of Gravemind, whose Flood followers have now taken over a huge Covenant ship called High Charity. Arbiter and Chief, now controlled by the player again, race to the Halo control to stop the Covenant from firing the ring one last time. They are successful in stopping the Covenant, but the Prophet of Truth, the last of their leaders escapes on a spacecraft unharmed. Chiefs AI companion Cortana stays behind on the Halo, promising to destroy it if any Covenant ever return. Chief and the Arbiter part ways with Chief hiding out on a fleeing Covenant ship and the Arbiter and his followers returning to High Charity in an attempt to save it from the Flood.

Development and release 
Halo 2 was officially announced in 2002. A game play video was shown at E3 2003. The video showed new features in the game such as dual wielding and the improved graphics. According to Bungie, the cliffhanger ending of the games story was not originally intended but was a result of the rush to get the game out on time.

Reviews and Sales

Sales 
Halo 2 was first released in North America and Australia on November 9, 2004. It was launched in Europe a day later on November 10. Demand was high for the game and over 1.5 million copies were sold on pre-orders alone. It was the highest earning entertainment product launch of all time in the US, earning $125 million in its first 24 hours. It held this record until the release of its sequel Halo 3. Halo 2 has sold over 8 million copies in the US making it the best selling original Xbox game of all time.
From the day of its release until 2006, 2 years later, Halo 2 was the most played game on Xbox Live. It was eventually beaten by the Xbox 360 game Gears of War.

Reviews 
The game was reviewed as excellent by most of the media. The sound work such as the dialogue and soundtrack was often praised.
The game received an average score of 95% on Metacritic, a website that puts together many reviews from different sources. The games multiplayer was often seen as a good point, making full use of the then new Xbox Live service. Bad aspects pointed out included the short length of the story mode and the cliffhanger ending.

References 

2004 video games
Xbox games
Windows games
Halo