Free massive multiplayer online first person shooter software for linux

Alpha Shooter is a 3D OpenGL first-person shooter game with a sci-fi setting.
Alpha Shooter was born as a project for the Computer Graphics course at the University of Bologna.
The main objective was to develop a very simple 3D game using the OpenGL, GLU and GLUT libraries only (and some creativity). Emphasis was not placed on the game itself, rather on learning how to use the libraries to produce a 3D environment and interact with it; it was thus required to build a suitable scenery using polygonal meshes and quadric surfaces, appropriate textures and materials, lights, and effects.
According to my personal taste I chose a sci-fi setting, trying to reproduce an environment that could remind players of a warehouse or loading area located inside a space ship or space station, like those often seen in movies or commercial videogames (of course I was aware of the limits of my implementation). I focused development on a single room, with an outside view, for ease of development (it was my very first attempt at graphics programming) and because it was enough to make use of a wide set of elements of OpenGL, consistently with the project requirements.
The game I wrote was inspired to the First Person Shooter genre, in which the player can move around in a 3D environment, looking around freely through the eyes of the played character, interacting (in very limited ways) with some of the objects present, shooting crates and barrels and some holographic targets.
I had a lot of fun creating that simple game, so after I got my Masters Degree I decided it would be a waste to just leave it hidden in some obscure directory at home; it is now here, released as Free Software, so that I can keep working on it and improving it, with help from whoever will be interested, in the hope that it will be useful as an example on how to get started in computer graphics and games development.
Enhancements:
- Binary packages were created for all supported operating systems, including a Windows installer, an i386 Debian Linux package, and a PowerPC Mac OS X DMG disk image.
- Additionally, the improved persistent mouse movement mode uses a dynamic mouse cursor that shows direction and speed of rotation, making that movement mode more intuitive and useful.
- Several minor bugs have also been fixed.

Regnum Online is a MMORPG game, that wants to invite you to join our world and play for free. The only thing we require is that you fight for your realm.
Regnum Online is a massive multiplayer online role playing game (MMORPG MMORPG) for the PC where the player are immersed in a 3D virtual world. There they can live as Elves, Humans Dwarves, or Dark Elves having exciting adventures, exploring the wild lands or joining an army of players to take on the other kingdoms armies."
The game is in beta stage, but already offers many quests, items, and monsters, not to mention the large number of both english-, spanish-, and portuguese-speaking players youll meet in-game.
Main features:
- Regnum offers 3 realms to choose from.
- 9 fully customizable player characters.
- Hundreds of quests.
- The ability to capture forts and castles.
- Expansive lands to explore.
- Glorious graphical environments.

Tactical Operations: Crossfire is a tactical shooter based on Unreal Tournament 2004.

Tactical Operations: Crossfire is a fast paced first person online shooter in which two teams, terrorists and special forces, duke it out in a wide variety of environments with various objectives to accomplish. From rescuing hostages kept in a small desert town in Saudi-Arabia to preventing the bombing of an oil refinery on the Caspian sea shore. There are no less than fourteen official maps to choose from!

Each map is played for a certain amount of time and the team having won the most rounds when the time runs out is declared the winner. A round can be won either by completing the objective set for that team, such as rescueing the hostages, or by simply eliminating all players on the opposite team.

A large number of weapons is avaialable for both teams, which can be purchased by each player at the start of the round. Out of the thirty weapons currently available, theres bound to be a weapon to suit your style of playing, be it either up close and personal with the Benelli Nova tactical shotgun or sneaky sniper work with the Dragunov SVD.

Tactical Operations: Crossfire continues where the popular Tactical Ops: Assault on Terror left off, with many classic weapons returning and remakes of some of the original maps. To play TO:C, you will need Unreal Tournament 2004 installed and patched to the latest version (3369). Tactical Ops: Crossfire can be played on Windows, Linux and Mac systems.

Open Space Shooter is a simple 2D space shooter like asteorids.

Just a small spaceship, some Asteorids and some enemies. You got lasers and rockets and try to fight the enemy ships, not more.

It is simple but funny.

All is just a prototyp of a game I want to write later. But I have no time at the moment...