Salut,
http://www.urbanterror.net/page.php?11Urban Terror is a mod for Quake 3 Arena. Urban Terror can be freely distributed ***spam*** the internet, unmodified, without charging for the product. Urban Terror uses the Quake 3 SDK license. This means the game code (the .qvm's in zpak000.pk3) are closed source and can only be distributed electronically ***spam*** the internet, not on cd or dvd. The non-code data files of Urban Terror (zpak000-assets.pk3) can go on any medium however. The full license texts come with the installer, they outweigh the information provided here.
Donc Urban Terror n'est pas un jeu libre, seule une partie (le moteur) est libre.