Half-Life 2 is a first person shooter video game created by the company Valve Corporation and released in 2004. This game is the sequel to the original Half-Life video game which came out in 1998. It is sold through the "Steam" sales system also developed by Valve. (Steam is a gaming platform where all games made by Valve can be played.) It is also available in The Orange Box, along with Half-Life 2: Episode One and Half-Life 2: Episode Two (sequels to Half-Life 2), Portal, and Team Fortress 2. Half-Life 2: Episode 3 is currently in development. Half Life 2 is based on a game engine called Source. There have been many other Source-based games, such as Portal, Team Fortress 2, Counter-Strike: Source, and Garry's Mod.
Half-Life was a very popular video game, and Half-Life 2 was also very popular. Many reviewers believe Half-Life 2 is better than Half-Life and one of the best games ever made. It took six years to create Half-Life 2 (from 1998 to 2004). It was supposed to be released in 2003, but it was not ready. Many fans were very angry and said Valve lied to them. However, it did release the next year (2004). It had much better graphics than Half-Life. It also had more complicated non-player characters and more of a story.
In Half-Life 2, the player is Gordon Freeman (the same character as in Half-Life). It begins about 10 or 20 years after Half-Life. The Combine, a group of evil aliens, took over Earth and made humans their slaves. Gordon Freeman wakes up on a train in a place named City 17. He finds the resistance, some humans who fight the Combine. In the game, he must help them and fight with them. The game ends with Gordon Freeman stopping Doctor Breen, the evil human who is helping the Combine.
There are many important characters in this game other than Gordon Freeman. Some are Eli Vance, who worked at Black Mesa with Gordon Freeman before the Combine came. He is part of the resistance. Alyx Vance is Eli's daughter. She travels with Gordon in part of the game. Doctor Mossman also worked at Black Mesa. She works with the resistance, but is also a traitor who helps Doctor Breen. Barney Calhoun was a guard at Black Mesa. Now he leads the resistance.