Doom was officially ported to Linux in 1994, and a modified version of Linux Doom was made source-available in 1997, then open-source (GPLv2) in 1999. It was one of the first high-quality open-source games. Those versions do not work on current Linux distros, but they have enabled modern source ports such as PrBoom+ and Chocolate Doom to be developed, and those are available in nearly every distro’s repository.
“I can’t stop the heterocyclic declination!” (TNG: “Samaritan Snare”)