Wolfenstein: Enemy Territory is a first-person-shooter game from Activision. At QuakeCon 2010, co-founder and Technical Director John D. Carmack announced that the source code for this game is now under the GPLv3.
Enemy Territory: Legacy is an open source "Binary compatible with Wolfenstein:ET" build stemming from the complete release of the source code in 2010. The last official W:ET build before going open source was named Wolfenstein: ET 2.60b, which is still played by a lot of players worldwide, and it is still supported by the open source version, but only if you are using the 32-bit version. Very few servers support 64bit at the moment.
You will need an accelerated 3D graphics card driver. If you have an Nvidia or ATI graphics card, and an accelerated driver was not enabled by default, then you can read instructions for obtaining a proprietary driver in BinaryDriverHowto
64-bit Ubuntu 14.10
sudo dpkg --add-architecture i386 sudo apt-get update sudo apt-get install libc6:i386 libdrm2:i386 libexpat1:i386 libgcc1:i386 libgl1-mesa-glx:i386 libglapi-mesa:i386 libglu1-mesa:i386 libstdc++6:i386 libx11-6:i386 libx11-xcb1:i386 libxau6:i386 libxcb1:i386 libxcb-dri2-0:i386 libxcb-dri3-0:i386 libxcb-glx0:i386 libxcb-present0:i386 libxcb-sync1:i386 libxdamage1:i386 libxdmcp6:i386 libxext6:i386 libxfixes3:i386 libxshmfence1:i386 libxxf86vm1:i386 libasound2:i386 libasound2-plugins:i386
64-bit Ubuntu 18.04
sudo dpkg --add-architecture i386 sudo apt update sudo apt install libasound2-plugins:i386 libdrm2:i386 libexpat1:i386 libgl1-mesa-glx:i386 libglu1-mesa:i386
Wolfenstein: Enemy Territory
Enemy Territory: Legacy
Note: The 64 bit version is not compatible with Enemy Territory 2.60b mods.
Current stable release is 2.75. However, it doesn't work in full screen mode. In this case it is recommended to use 2.74. Grab the Linux installer and run it. For 32 bit:
wget -O etlegacy-v2.74-i386.sh https://www.etlegacy.com/download/file/74 chmod +x etlegacy-v2.74-i386.sh ./etlegacy-v2.74-i386.sh
Accept the GPL v3 license and install it wherever is desired, by default the same directory your current path is in the terminal. At this point it will ask you if you want to fetch the assets data files. This is needed to play the game, and the installer will extract everything as needed. On the next prompt you can delete downloaded assets data files.
Do you want to fetch the assets data files? [yN]: y Fetching Wolf:ET assets data files...
Do you want to delete downloaded Wolf:ET assets data files? [yN]: y
And now you are ready to play!
cd etlegacy-v2.74-i386 ./etl