I'll never forget installing ut2k4 on my linux box and having it Just Work. Magical.
Not just working, but it actually ran better in Linux for me -- my university-mandated laptop could only run it at 1280x800 in Windows if you wanted to hit 60fps, but the Linux client was able to run at the panel's native 1920x1200.
I had it working without issues from Steam (I bought UT 99 and 2004 before Epic de-listed from Steam)
Not just working, but it actually ran better in Linux for me -- my university-mandated laptop could only run it at 1280x800 in Windows if you wanted to hit 60fps, but the Linux client was able to run at the panel's native 1920x1200.