Urban Terror is a free, fast paced multiplayer FPS game which started out as a mod for Quake III. Popularly called UrT, this game is focused on fun, addictive gameplay with bits of reality thrown in. There are a variety of weapons to choose from, and all of them closely resemble their real life counterparts. There are plenty of maps to play on, and more can be downloaded, so you should never get bored. There are plenty of different game modes like team deathmatch, bomb mode, team survivor, capture the flag, free for all etc. This game can be played over a LAN or on the internet. Anybody who has played this game with more than 4 players can testify to its addictiveness! You can run this game on Windows, Mac, or Linux.
You can find lots of download links on this page. The .zip version works on all OSes, while the .exe version works only on Windows OSes.
Screenshots can be viewed here.
All new UrT gamers are requested to read the Urban Terror Manual and the FAQ. These will clear a lot of your doubts.
My trigger-happy fingers are itching for some action, so I’ll be off now. Maybe I’ll see you next time I play. 
