This is a very good multiplayer game with modes such as CTF and Skirmish
Cubemen 2, a funny 3D strategy game developed and published by 3 Sprockets studio, is available on Steam for Linux with 25% discount.Cubemen 2 is a game in which players have to use their units, called Cubemen, to defend and attack enemies in a multitude of modes, including CTF, Skirmish, Territory, and more.
The game also features a generous multiplayer, and players can compete in up to 6 players online Solo or Team battles, either with a human partner or with the AI.
The hardware requirement are medium and most users will be able to meet them
Linux System Requirements:
OS: Ubuntu 12.04 +
Processor: 2 Ghz Intel or AMD
Hard Disk Space: 200MB
Video Card: OpenGL 2.0 Nvidia 8000, Radeon HD3000, Intel HD ( No GMA9xx )
Sound: OS Compatible sound card with latest drivers.
More details about this game can be found on the official Steam website.