The Fallout series was originally owned by Interplay, a company that had very hit-or-miss luck with the IP. They created the first and second games in 1997 and 1998. After that, the company produced a couple spinoff Brotherhood of Steel games, including a notoriously buggy tactics game. In a little over a decade, Interplay had produced four games under the Fallout title but had also cancelled production on four other games.
These sunken games are largely what prompted Interplay to sell the Fallout IP to Bethesda in 2007. Each has its own tragic backstory.