It will be a while before Bethesda releases a new Fallout game, but in the meantime, some enterprising fans have taken it upon themselves to release a major update for Fallout 4.

"Fallout: London" is now available for free download via GOG and is compatible with the Steam version of Fallout 4. However, there's one caveat: you'll need to be using the version of the game that predates the recent next-gen update. A next-gen compatible version is also in development, though no release date has been announced at this time.
See related: Fallout Coming to Fortnite's Next Season on PS5, PS4
As of 2019, the London mod introduces a new location and story to the post-apocalyptic world, featuring fully voiced characters and 200 different missions. It is estimated to offer around 90 hours of gameplay. Here is the official description from developers Team Folon:
“True to its name, Fallout: London is set in the heart of London. From the submerged parliamentary aristocracy to the revival of the Knights of the Round Table to a ruthless cult of revolutionaries (and beyond), Fallout: London embodies the city’s history and aesthetic , bringing an unmistakable nuclear dimension to this beloved metropolis.
The mod comes at a good time, as Fallout is enjoying a particularly prime spot thanks to the excellent live-action series on Amazon Prime Video, which has already been renewed for a second season. While no new single-player Fallout game has been announced, Bethesda just released a major update for the online spinoff Fallout 76.

Read more: Fallout 4: Fans demand an end to Bethesda updates
Meanwhile, the studio is preparing to release the “Shattered Space” update for Starfield this year, while also working on a new Elder Scrolls.
Source: theverge
