Fallout 3 from the creators of the award-winning Oblivion, featuring one of the most realized game worlds ever created. Create any kind of character you want and explore the open wastes of post-apocalyptic Washington D.C. Every minute is a fight for survival as you encounter Super Mutants, Ghouls, Raiders and other dangers of the Wasteland. Prepare for the future.

The third game in the Fallout series, Fallout 3 is a singleplayer action role-playing game (RPG) set in a post-apocalyptic Washington DC. Combining the horrific insanity of the Cold War era theory of mutually assured destruction gone terribly wrong, with the kitschy naivety of American 1950s nuclear propaganda, Fallout 3 will satisfy both players familiar with the popular first two games in its series as well as those coming to the franchise for the first time.

The introductory sequence introduces the player to their character's father James, a doctor and scientist in Vault 101. James frequently makes comments about the player character's deceased mother Catherine, and her favorite Bible passage, Revelation 21:6, which speaks of "the waters of life".

The main quest begins after the player is forced to flee Vault 101 when James leaves the vault, throwing it into anarchy and causing the paranoid Overseer to send his security force after the player. The search for James takes the character on a journey through the Wasteland, first to the nearby town of Megaton, named for the undetonated atomic bomb at the center of town, then the Galaxy News Radio station, whose enthusiastic DJ Three Dog gives the player the moniker of "The Lone Wanderer". The player travels to Rivet City, a derelict aircraft carrier now serving as a fortified human settlement. Here the player meets Doctor Li, a scientist who worked alongside the player's father. Doctor Li informs the player of Project Purity, a plan conceived by Catherine and James to purify all the water in the Tidal Basin and eventually the entire Potomac River with a giant water purifier built in the Jefferson Memorial. However, continued delays and Catherine's death during childbirth put an end to the project, and James took the player's character as a newborn to raise them in the safety of Vault 101.

After investigating the Jefferson Memorial, the Lone Wanderer tracks James to Vault 112, and frees him from a virtual reality program being run by the Vault's sadistic Overseer, Dr. Braun. James and the player return to Rivet City, and James reveals he sought out Braun for information on the Garden of Eden Creation Kit (G.E.C.K.), a device that contains the components needed to finally activate Project Purity. James and Doctor Li lead a team of Rivet City scientists to the memorial with intent to restart the project, but the memorial is invaded by the Enclave, a powerful military organization formed from the remnants of the pre-War United States government. James floods the project's control room with radiation to stop the Enclave military leader, Colonel Augustus Autumn, from taking control of it, killing himself (but Autumn survives), his last words urging his child to run. The Lone Wanderer and Dr. Li flee to the ruins of the Pentagon, now a base for the Brotherhood of Steel and now known as the Citadel.