If you haven't done so yet, you should go over the content of the linux Q3A faq first. Quake III Arena linux and Wolfenstein linux have a lot of code in common, and the issues that are known to both games are reported in the Quake III Arena FAQ sometimes.

If you are looking for help with the Multiplayer demo, go to the Multiplayer demo FAQ page.

• Installation instructions
• TuxGames's Return To Castle Wolfenstein installer
• The setup crashes with Segmentation fault "$setup" "$@" 2>/dev/null
• Installation on BSD
• sig 11 right after loading qagame in single player
• CLIENT_UNKNOWN_TO_AUTH
• Sys_Error: Couldn't load default.cfg / Sys_Error: FS_FreeFile( NULL )
• What command do I type to run the server?
• vm_game 0 or vm_game 2 ?
• The game doesn't start, I have performance problems, etc.
• The sound doesn't work / sound crashes
• Setup and execution on 64 bits CPUs
• Links

Return to Castle Wolfenstein linux is using a graphical installer (based on Loki software's Setup Graphic Installer). This process is documented in the INSTALL file (this file is available when you run the setup). The .x86.run files are meant to be executed (you may need to make them executable with chmod +x file.x86.run).

TuxGames provides an installer for Return To Castle Wolfenstein. Please note that this is not endorsed by id software, and it is not required for installing Return To Castle Wolfenstein on Linux. The installer is intended to make the installation easier by going through the steps described in the INSTALL file for you.

Actually, I could never get TuxGames's RTCW installer to work. I can't help you if you can't make it run, but I got some feedback about it otherwise:
It looks like the installer uses symlinks in your ~/.wolf directory to install the files. This is likely to break when you update to a new version of RTCW through id's official setups. You have been warned.

See the related answer in the q3a FAQ.

See the related answer in the q3a FAQ.

On RedHat 7.2, /usr/lib/libgdkxft.so (Anti-Aliased fonts) is preloaded and crashes Wolf SP for an unknown reason. In your terminal, type unset LD_PRELOAD to avoid the preloading and you should be fine.
Thanks to Trevor Phillips for finding this one.

See the related answer in the q3a FAQ.

See the related answer in the q3a FAQ.

This is documented in the QUICKSTART file (also installed locally by the setup). See the links section to find websites dedicated to server administration for more.

This is the main difference between Return to Castle Wolfenstein and Quake III Arena linux servers: The Wolfenstein server is running the game with native shared objects (.so), and not with virtual machine. You must set vm_game 0 to run the server, otherwise the game initialization will fail.

See the related answer in the q3a FAQ.

See the related answer in the q3a FAQ.

See the related answer in the q3a FAQ.

The Linux Gamer's faq is a very good resource for general Linux Gaming topics.

Quake3World's linux FAQ
Linux FAQs for id software products