Vault 101

Vault 101 is a fictional underground fallout shelter in Virginia and the tutorial area for the player character, referred to as the "Lone Wanderer," in the 2008 action role-playing game Fallout 3, created as part of the Fallout franchise by Bethesda Game Studios. Set in an alternate timeline of the United States, it was among many vaults that were created for human shelter from nuclear fallout by the Vault-Tec Corporation, but were also used to experiment on their unwitting residents. Vault 101 in particular was meant to keep its residents permanently isolated within. Since the "Great War of 2077" that caused the United States to be obliterated by nuclear attacks, Vault 101 had remained mostly shut from the outside world, since then a radiated wasteland, for the next 200 years.

In the game's lore, James was a scientist collaborating on a water purity project for the residents of Washington, D.C. who took a hiatus shortly after his wife died from giving birth to the player character, arranging a deal with Vault 101's overseer to allow them to stay there. The game, through the protagonist's coming of age, introduces the player through in-universe tutorial sequences that allow them to allocate in-game abilities and teach them about gameplay mechanics. In 2277, after Amata, the overseer's daughter and the Lone Wanderer's best friend, informs them of the player character's father's departure from the vault and warns them of the overseer's escalatory lockdown responses, the player character makes an escape to the wasteland for safety and to find their father, who left to restart the water purity project. Near the end of the game, the Lone Wanderer can choose to return to the vault one more time after Amata contacts them using an emergency signal via their Pip-Boy to resolve issues regarding the overseer resisting against residents' efforts to leave it. Vault 101 has received positive receptions as an effective and immersive tutorial location, most notably as an area that the Lone Wanderer had long grown up in but was forced to eventually abandon in favor of the harsh outer wastelands.