Multiplayer games you can get for free

It's amazing what you can get for free these days. Open source has completely changed how people think about software. I can get a new computer and completely stock it with everything I need for my daily activities through open source software and online services. The quality of open source software has also greatly improved over the past few years, with some areas actually going beyond what you can buy. The exception to this has always been games. Sure, you can get lots of free games online, but none match the quality of some of the titles at the store. There seems to be a shift lately in this arena though. I see more and more quality games being released free. The availability of some of the lower level tools like 3D engines, graphics programs, and modelers seem to be fueling this effort to create high quality games released free. I'm going to list some of the ones that I was actually surprised to find are now free.

This is by no means a complete list of free games available. I tried to put together a list that gave varying weights to quality, cross-platform compatibility, and community. It's hard to play an online multiplayer game without multiple players.  Again, this is not a complete list of free games.  If I've played it, looked at the community, and think it holds up, then it goes on the list.  

First-Person Shooters

F.E.A.R. -- The multiplayer component of F.E.A.R. called F.E.A.R. Combat is free, just sign up at their web site for a key and download the game. You can play against retail owners of the game, as well as, other F.E.A.R. Combat users.

America's Army -- This is a game put out by the U.S. Government as a recruitment tool. The graphics in this game look very good and they continue to update it. The web site boasts that it has 7.9 million players.

Urban Terror -- A counter-strike-like Quake 3 mod that is now a full game.  Lots of weapons, maps, and players. 

Return to Castle Wolfenstein: Enemy Territory -- This game was originally slated to be a expansion pack for RoCW, but after some problems with the single-player component, it was released for free. The game logic was open-sourced, and the Quake3 engine that runs it is also open-sourced.

True Combat: Elite -- Tactical-teamplay shooter that is one of the best mods for the above Enemy Territory.

Starsiege: Tribes -- One of the first online-only multiplayer games was also one of the best. Plenty of people still play Tribes 1.

Tremulous -- From the website, Tremulous is a free, open source game that blends a team based FPS with elements of an RTS. Runs on the Q3 engine also.

Alien Arena -- Has a Quake-like play, a good stat system, and nice community support.

Cube 2 -- Cube 2 is a free multiplayer/singleplayer first person shooter, built as a major redesign of the Cube FPS.

Nexuiz -- This game has been talked about on here before, but I had to list it again. It has good community support, is open source, and was released under the GPL license.

Warsow -- Features all the classical moves that Quake offered along with more special moves for players like the wall jump and ramp slide.

War Rock -- Soon to be released, War Rock is a free FPS that is among the top downloads on FilePlanet.com

Free Allegiance -- The only space simulation game on the list. Has a solid community following.

Open Arena -- Q3 clone that is aiming to work with all Q3 mods. Has bots and several dedicated servers for gameplay.

Legends -- Tribes-like gameplay and cross-platform compatibility based on the Torque game engine.

MMORPG's

Archlord (Review) -- P2P game that went free recently, has castle sieges, good PvP system, lots of quests, and an opportunity to become archlord.

RF Online -- Sci-fi fantasy game that has faction-based PvP, guild battles, and resource wars.

2Moons -- Supposedly a MMORPG set in a volatile world that challenges you to survive.

Rappelz (Review) -- This game looks like it has lots of options for players, as well as having a very active community for support.

Knight Online -- According to Download.com, Knight Online has over 6 million downloads, and 300,000 people playing at any one time.

Shadowbane -- Previously a pay-to-play game, UBI has quietly released this game free to the public.

Anarchy Online -- Another pay2play game that was released free to the public a while ago. I like the concept, and glad it's not yet another fantasy hack and slash.

MU Online -- With real player vs. player combat and weather effects, you might not believe this game is free. With a solid guild and party system, you'll be making friends in no time.

Eudemons Online -- It has decent graphics, offers players the chance to go pk, and a mentor system.

Hero Online -- In beta right now, Hero Online has one of the most active communities I've seen in a free game. Created by martial arts novelist, the game focuses on skills and movements.

Silk Road Online -- Even though it's a European fantasy based MMORPG, I'm told Silk Road Online has plenty of english speaking players to interact with. This is supposed to be a lot like World of Warcraft, except free.

Legend of Ares -- From the creators of Hero Online come this realm vs. realm pvp-based rpg. Also features a honor system.

Rakion -- I was really unsure where to put this since Rakion bills itself as a MMORPG strategy action game. If your looking for a game that covers it all, this may be for you.

Last Chaos -- Good graphics and interesting features such as its Player vs. Player vs. Environment bringing PvP and PvE together are what puts Last Chaos on this list.

9Dragons (Review) -- One of the only U.S. based free to play MMORPGs on the list, 9Dragons has great graphics, a lot of options for characters, and one of the best PvP systems there is.

Strategy

Command & Conquer Gold -- Popular RTS that went free for it's 12th anniversary.

Battle for Wesnoth -- This turn-based strategy game has quite a following in the Linux world, although it's freely available to Windows and Mac users.

FreeCiv -- An empire-building strategy game inspired by the history of human civilization. Been in development a long time and improvements keep coming.

Spring -- Boasts large battle support, large maps, good AI, and many different mods. Has some very detailed graphics.

Savage: The Battle for Newerth -- This is a real-time strategy shooter that has decent graphics and a different kind of gameplay for those looking for something out of the ordinary.

Invasion: Battle for Survival -- Not a lot of explanation on the web site, but the graphics look decent for a real time strategy game.

BZFlag -- Not the best graphics in the world, but the tank battle BZFlag has some great gameplay, low hardware requirements, and runs on a lot of different operating systems.

There you have it, some of the best and the brightest from the world of free multiplayer games. With some of the games on this list, I wonder why I ever paid to play at all.