RealRTCW is a community single-player overhaul project for Return to Castle Wolfenstein based on the iortcw and rtcw-sp source code.
Features:
The original id software readme that accompanied the RTCW source release is named README.txt and is contained within the source tree of both MP and SP games.
Available on ModDB: https://www.moddb.com/mods/realrtcw-realism-mod
And on Steam: https://store.steampowered.com/app/1379630/RealRTCW/
Arch Linux Repo by M0Rf30: https://aur.archlinux.org/packages/realrtcw/
Opensuse package: https://build.opensuse.org/package/show/games/realrtcw