(Note that Fallout London is a fan-mod, not an official new fallout game)
First issue was the downgrade failing to run because it claimed I was missing an ssh library. Then I found a work around that involved grabbing the uncompiled source and running the script from there, but that failed to connect to steam. I finally downgraded using a manual method that took forever, but it worked. Once I finally got it all running, I hit the infamous crash after the train ride bug.
Ah that’s unfortunate. Which distro?
They included Buffout 4 in the latest patch, so hopefully thus issue won’t be affecting more players in the future