@eevee For DOOM I think they did some bizzare in-house remake in Unity or something. The giveaway was a few megabytes of game that was just the WAD files I needed for gzdoom et. al. suddenly balooning into a gig-plus of a port I will never use. Thanks Bethesda.

https://doomwiki.org/wiki/Doom_Classic_Unity_port

(Yes yes Unity has a Linux build and it might even work on one or two distributions if you're using Pulse but not Pipe and not raw ALSA and X and not Wayland and bluh bluh bluh.)