Fallout is a series of post-apocalyptic role-playing games created by Interplay.
The series was introduced in 1997 with the release of Fallout: A Post Nuclear Role Playing Game, being followed with a sequel in 1998. Until 2003, a third installment was planned, codenamed Van Buren. The game would have used a similar playstyle to the other two installments, and was due to use an engine called the "Jefferson" engine.
Black Isle Studios, which was shut down by Interplay in 2004, leaving Van Buren behind. The Jefferson engine, along with the game, was almost complete at the time of cancellation. Shortly after, Interplay started to work on an action game with role-playing elements for the PlayStation 2 and Xbox, released in 2004 by the name of Fallout: Brotherhood of Steel.
After the cancellation of Van Buren, the single-player rights to the Fallout series were sold to Bethesda Softworks. Bethesda proceeded to start working on their own third installment, unrelated to Van Buren, following a different direction to the previous two installments. As opposed to the previous installments, the game used both a third-person and first-person perspective, with both real-time combat and timeturn-based combat. Bethesda's Fallout 3 released in 2008.
Due to Fallout 3's success, Bethesda was keen to release a sequel. However, most of Bethesda's workforce was currently assisting development of The Elder Scrolls V: Skyrim. Instead, Obsidian Entertainment would publish the game, with Bethesda assisting development and ultimately publishing the game. The game was later revealed as Fallout: New Vegas.
Fallout: New Vegas used several aspects of the cancelled Van Buren, including some locations and factions, although being similar to Fallout 3 in a technical aspect, as they both used the Gamebryo engine. The game was officially revealed during E3 2010, and was released later that year.
Fallout 4 was officially announced during E3 2015, although being leaked several months earlier, which ultimately finished development on October 23, 2015. The game was released for Microsoft Windows, the PlayStation 4 and the Xbox One on November 10, 2015.