Fallout: London is a truly impressive mod, according to PCG writer Joshua Wolens—that is when you're able to actually get it working and navigate all the performance issues and bugs. 

Since the mod's release, players have reported a few game-ending crashes, including one fondly named the “train crash,” which has plagued most players. Not only will boarding the train to navigate apocalyptic London likely lead to your game crashing, but it will also cause a strange bug that halves players' HP. 

“The issue with the train crash is quite a known one, and it's been reported on quite a lot,” project manager Dean Carter says in an interview with VG247. “We never had that. We wouldn't have released if we had that. None of our testers had that. So we're not sure if something actually happened with the final upload or something, but it’s those sorts of ones that have been a bit of a surprise to us.”

“You put your heart and soul into anything, and eventually you sort of realise, no matter how hard you've worked, everything's held together with duct tape. So, [Fallout: London's] held together better than we thought, but lots of the issues that we've had, or people have been reporting rather, they’re not ones that we had.”

Fallout: London devs Team FOLON has promised to release a huge hotfix ASAP, but in the meantime, the only solution for the HP bug after the train crash is to complete some math homework. 

“I believe the order we're going to do it in will be a hotfix that should basically include things like [the] Buffout 4 [mod],” Carter says, “So, the sort of systems that people have said are almost a requirement to run, we went and got permission for those. We didn't have permission before, which is why we never really mentioned them, and they were things that people had to go and get. Since we've released, obviously, they're more inclined to want to work with us now, so now we're gonna do a hotfix that should include things like Buffout 4, which will help stability and those issues.”

Some of the issues can be remedied pretty easily without the help of a hotfix. If you encounter a problem, then the first port of call should be to check out the Solutions Megathread that Team FOLON put together. Sometimes, crashes and bugs can occur by not following the correct download steps. 

“The biggest gripe that we've had is when people have installed things wrong, and then they have stated that it's our fault,” Carter says. “We know it's not the easiest install on Steam. We do understand that, and we have tried our best. But yeah, when it comes to those sorts of things, we have got a tech support team that's been helping.”

We found that installing Fallout: London can be quite an unforgiving experience. Thanks to the next-gen update for Fallout 4 messing up Fallout: London's compatibility, you'll need to downgrade your version to play the mod. Team FOLON previously announced that the newest Fallout 4 version “isn't stable enough.”

But despite all the technical difficulties, Carter still admits that Fallout: London's launch has been fairly successful overall: “In terms of the release itself, it's actually gone a lot better than we thought it would.”