I thought it would be fun to search out some free FPS (i havent tested them all) but this list comprises of what i thought would be fun to play and/or that seems at all decent and best of all FREE!. I've included links to the internode file library where possible.
Feel free to take a look.
Alien Arena O7
A fully functioned free deathmatch shooter. Features standard deathmatch, team deathmatch, capture the flag, Deathball, and all out assault, in a 50's era sci-fi atmosphere. There are 37 maps, 10 playermodels, and 8 weapons. Gameplay is similar to Quake III and UT2004. The game features visual effects such as shaders, stencil shadows, light bloom and reflective water, and highly detailed models and textures.
Most people should know what this game is by now. If you dont WTF go and play it. (current build is America's Army: Special Forces (Overmatch) v2.7)
Yeh all the rage nowdays. Pretty fun. Make sure you get it.
Hidden & Dangerous
A WW2 FPS/3rd Person tactical shooter. A little old but fun to play. Couldnt find and official site but use the link below to get more info / screenshots.
Use the Internode mirror under public servers:
I didnt test this one personally but it looks pretty awsome. Here is the run down. An FPSs game that focuses on quick, lethal battles with balanced weaponry. As of this release there are 9 weapons and 17 official maps, as well as 15 player models, with an average of 2 skins each.
An FPS horror adventure game. The game makes heavy use of advanced graphics and physics, allowing for a great deal of interaction between the player and the environment. The physics engine in Penumbra is very flexible and realistic. Like many current computer games, objects aren't fixed in place. For instance, you can pick up boxes and pile them on top of each other, move shelves, open doors, throw things around or drop them down stairs, and more. This allows for a very immersive game world, as well as challenging puzzles.
Never tested this one but aparently its a partially open source Quake-like first-person shooter. The game uses OpenGL and SDL, features single-player and multiplayer gameplay and contains a built in level editor. Sauerbraten is a branch of the computer game Cube and expands its original concept. It shares most of design goals and philosophy with Cube, but uses a new 6-directional heightfield world model. This allows much more complex level geometry and easier editing. Much like the original Cube, the aim of this game is not necessarily to produce the most features & eyecandy possible, but rather to allow map/geometry editing to be done dynamically in-game, to create fun gameplay and an elegant engine. The engine supporting the game is entirely original in code & design.
Internode (i dont think this is the actual game though, not sure):
Didnt test this myself but apparently the game is team based, with players taking on the role of a human mercenary or a vicious alien. Their objective is to destroy the opposing team's base while simultaneously defending and maintaining their own. Both sides of the conflict earn points for making kills. Humans earn credits, which are used to buy superior equipment and weapons. Aliens earn evolution points which are used to become larger and more powerful.
Didnt test but Some Features Include:
* 3D Engine based on Qfusion (a modification of Quake 2 GPL engine)
* eSport oriented FPS
* Fast-paced gameplay focused on trix (trick jumps) and art of move
* Complete Power-up System including Weak and Strong fire mode for each weapon
* Cartoonish cel-shaded graphics
While still technically in its beta stage (with periodical stable releases), War§ow is already gaining immense popularity by being featured in international video game tournaments such as the Cyberathlete Amateur League.
Wolfenstein: Enemy Territory
Everyone should have at least had a go at this at some point. Pretty much The wolfenstein version of Quake wars. Give it a try its recomended. im not sure about the online popularity anymore though.
(you can use the internode mirror)
Ok so here are some other off the bat random games that i thought i might include if you want the Internode link look for it yourself lazy bum.
Dink Smallwood (a mega LOL)
If i get some time i might make a Free MMORPG list.