Best way to play on Linux. For now...

[KingyWingy]

Use the windows version.
Use dgvoodoo 2 and set it to use Direct3D 12.
Apply these patches. https://github.com/aldehir/ut2004-patches
Set the render device to Direct3D 9 in the ut2004.ini file.

And ofcourse, replace DefOpenAL32.dll with the OpenAL Soft (windows 32 bit version) library renamed to DefOpenAL32.

[Romactu]

That's cool, I just better off with OpenGL and 64-Bit (It's not perfect but it's worth it for me).
Yes, there is a way to install the game and play the game if the game it's not poping up DirectX 9 installer there is a way to fix that.
https://steamcommunity.com/app/13230/discussions/0/4522262583805815366/