Quake 3.11 is a package of Quake 3 Arena, it runs from a stand alone executable and does not require installation to play. Quake 3.11 supports a custom soundtrack and can playback FLAC ond OGG Vorbis audio formats through the use of XIPH.org opencodecs directshow filter. Please note that Quake 3.11 requires one instance of being run as an administrative account to install these codecs. However without the administrative privileges one can still play (non-freeformat) MP3,WMA and WAV files. This is merely a launcher, not an actual modification of Quake 3 Arena. This launcher was scripted by Alex Schroedsen (alex.schroedsen) who does not claim to own Quake 3 Arena and does not profit from this release.
Instead of using the registration key entry system in the Quake 3 options, you can copy and paste a key to ensure no errors.