I'm surprised I hadn't heard of this one before! A few developers have been building Nazi Zombies: Portable, a Call of Duty: Zombies demake powered by various enhanced forks of the Quake engine.
FYI - the owner of this site, gamingonlinux, was a mod on the !linux_gaming@lemmy.ml community until they were caught abusing their moderator powers. Then they deleted their account and complained on mastodon that it's stupid design that mod logs are public. [Screenshot]