OpenArena is a Free Software first-person shooter that is multiplayer oriented.
AssaultCube,
formerly ActionCube, is a free first-person-shooter based on the game Cube. Set in a realistic looking environment, as far as that´s possible with this engine, while gameplay stays fast and arcade. This game is all about team oriented multiplayer fun.
Game Overview
Wolfenstein: Enemy Territory is a free, stand-alone, downloadable multiplayer game in which players wage war as Axis or Allies in team-based combat. It's a team game; you will win or fall along with your comrades. The only way to complete the objectives that lead to victory is by cooperation, with each player covering their teammates and using their class special abilities in concert with the others.
Welcome, my friends! In this article, I'll walk you through setting up a full-blown OpenArena server! Have no fear - by the end of you reading this, you'll have all the information you need to get a server up and running!