In development since 2019, the London mod introduces a new location and story to the postapocalyptic world, complete with fully voiced characters and 200 different quests. There’s an estimated 90 hours of gameplay included. Here’s the official description from the developers at Team Folon:
True to its moniker, Fallout: London takes place in London. From stuffy parliamentary aristocrats to a resurrection of the Knights of the Round Table to an uncompromising cult of revolutionaries (and more!), Fallout: London embodies the history and aesthetics of London and puts an unmistakably nuclear spin on the beloved city.