Team fortress 2

starts by saying hello to everyone, Team fortress 2 is  agood game for linux In Team Fortress 2, players join one of two teams comprising nine character classes, battling in a variety of game modes including capture the flag and king of the hill   
                                      
                                           

OS: Ubuntu 12.04
Processor: Dual core from Intel or AMD at 2.8 GHz
Memory: 1 GB RAM
Graphics: nVidia GeForce 8600/9600GT, ATI/AMD Radeon HD2600/3600 (Graphic Drivers: nVidia 310, AMD 12.11), OpenGL 2.1
Network: Broadband Internet connection
Storage: 15 GB available space
Sound Card: OpenAL Compatible Sound Card

 You can download from official website there