After the alien invasion at the Black Mesa Research Facility, a multidimensional alien empire known as the Combine invaded and subjugated Earth. Approximately twenty years after being placed in stasis, Gordon Freeman, the player character, is awoken by the G-Man, who cryptically informs Gordon that "his time has come again" before celestially inserting him into a moving passenger train bound for City 17, an Eastern European city which houses the Citadel, a several-miles-tall tower which serves as the headquarters of the Combine on Earth.
Like the original Half-Life (1998), Half-Life 2 is a single-player first-person shooter (FPS) in which players control Gordon Freeman. It has similar mechanics to Half-Life, including health-and-weapon systems (though with fewer overall weapons) and periodic physics puzzles, except with the newer Source engine and improved graphics. The player starts without items and widens their arsenal over the course of the game. While the game is mainly linear, effort was put into making exploration rewarding and interesting; many optional areas can be missed or avoided.
Source: Wikipedia, "Half-Life_2," available under the CC-BY-SA License.
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