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Me and my brother decided to find some decent multiplayer games to try over the weekend and here are a few that we came up with. These are all open source and free to play. At the bottom I have also listed some games which are free to play but which are not open source. Oh! and all of the games on this page are multiplayer which is perfect for a lan party or simply to play with friends. Why did we pick open source games? It’s always fun to pick apart games to see how they are built in order to learn new things!
Free and open source
Warsow - Awesome Looking FPS - http://www.warsow.net/media
This was a pretty fun game. Easy and quick to get started, works well with more than 2 players.
Warsow is set in a futuristic cartoonish world where rocketlauncher-wielding pigs and lasergun-carrying cyberpunks roam the streets. It is a completely free, fast-paced first-person shooter for Windows, Linux, and Mac OS X.
Speed and movement is what Warsow is all about. Like a true cyberathlete you jump, dash, dodge, and walljump your way through the game. Grab power-ups before your enemy does, plant a bomb before anyone sees you, and steal the enemys flag before they know what is going on!
FreeCiv - Civ 1/2 clone - http://freeciv.wikia.com/wiki/Main_Page
Freeciv is a Free and Open Source empire-building strategy game inspired by the history of human civilization. The game commences in prehistory and your mission is to lead your tribe from the Stone Age to the Space Age…
OpenTTD - Based on Transport Tycoon Deluxe - http://www.openttd.org
UFO:AI - Based on orig. XCOM - complicated - http://ufoai.org/wiki/News
Seemed like both players had to open ports in their routers to play online. The campaign seems pretty nice, a lot of story if you like that.
UFO: Alien Invasion is a squad-based tactical strategy game in the tradition of the old X-COM PC games, but with a twist. Our game combines military realism with hard science-fiction and the weirdness of an alien invasion. The carefully constructed turn-based system gives you pin-point control of your squad while maintaining a sense of pace and danger.
Over the long term you will need to conduct research into the alien threat to figure out their mysterious goals and use their powerful weapons for your own ends. You will produce unique items and use them in combat against your enemies. If you like, you can even use them against your friends with our multiplayer functionality. 0AD - Like Age of Empires - http://play0ad.com/
0 A.D. (pronounced zero-ey-dee) is a free, open-source, historical Real Time Strategy (RTS) game currently under development by Wildfire Games, a global group of volunteer game developers. As the leader of an ancient civilization, you must gather the resources you need to raise a military force and dominate your enemies. TripleA - Risk - http://triplea.sourceforge.net/mywiki
Much more detailed than the regular board game Risk, also had a lot of active players.
TripleA is a free online turn based strategy game and board game engine, similar to such board games as Axis & Allies or Risk. TripleA comes with multiple games and over 100 more games can be downloaded from the user community. Supports single player vs AI, hot-seat, Play by Email and Forum, and a hosted Online lobby for live play online.
Recreate World War 2 with the Axis pushing through to Moscow, Japan devouring the Pacific, and the Allies desperately fighting back. Or recreate Napoleon’s march across Europe, or Rome defeating the Carthaginian Empire, or Sauron conquering Middle Earth, or even Zombies taking over America! If you have ever played a game where you push little plastic/virtual pieces around, roll dice, conquer the lands of your enemy, & produce new pieces to conquer with, you will be able to jump right into TripleA! BZFlag - 3D tanks - http://bzflag.org/
BZFlag is a free online multiplayer 3D tank battle game. The name originates from “Battle Zone Capture The Flag”. It runs on Windows, Mac OSX, Linux, BSD, and other platforms. It was one of the most popular games ever on Silicon Graphics machines and continues to be developed and improved to this day.
Boswars - Command and conquer? - http://www.boswars.org
Bos Wars is a futuristic real time strategy game (RTS). In a RTS game, the player has to combat his enemies while developing his war economy. Everything runs in real-time, as opposed to turn-based games where the player always has to wait for his turn. The trick is to balance the effort put into building his economy and building an army to defend and attack the enemies.
Bos Wars has a dynamic rate based economy. Energy is produced by power plants and magma gets pumped from hot spots. Buildings and mobile units are also built at a continuous rate. Control of larger parts of the map creates the potential to increase your economy throughput. Holding key points like roads and passages allow for different strategies. Warzone - RTS, 400 techs, lots of customization - http://wz2100.net/
In Warzone 2100, you command the forces of The Project in a battle to rebuild the world after mankind has almost been destroyed by nuclear missiles.
The game offers campaign, multi-player, and single-player skirmish modes. An extensive tech tree with over 400 different technologies, combined with the unit design system, allows for a wide variety of possible units and tactics. Vdrift - Racing/Rally - https://code.google.com/p/vdrift-ogre/
VDrift is a cross-platform, open source driving simulation made with drift racing in mind. The driving physics engine was recently re-written from scratch but was inspired and owes much to the Vamos physics engine. It is released under the GNU General Public License (GPL) v2. It is currently available for Linux, FreeBSD, Mac OS X and Windows.
This game is in the early stages of development but is already very playable. Currently the game features:
Simulation-grade driving physics
Tracks based on famous real-world tracks
Cars based on real-world vehicles
Competition against AI players
Crossfire - RPG - http://crossfire.real-time.com/
Crossfire is a multi-player graphical arcade and adventure game made for the X Windows systems environment. It has certain flavours from other games, especially gauntlet and the rogue-like games (Nethack, Moria, Angband, and Ragnarok.) Any number of players can move around in their own window, finding and using items and battling monsters. They can choose to cooperate or compete in the same world.
Edit: Oops, hedgewars is actually open source and multiplayer, it has now been moved! :)
Hedgewars - Worms clone - http://www.hedgewars.org/
Hedgewars is a turn based strategy, artillery, action and comedy game, featuring the antics of pink hedgehogs with attitude as they battle from the depths of hell to the depths of space.
As commander, it’s your job to assemble your crack team of hedgehog soldiers and bring the war to your enemy.
Free to play but not open source
World of Tanks - 3D Tank Game - http://worldoftanks.eu/
I have been playing World of Tanks for a little over a year now. I haven’t played constantly but I go back to playing it all the time since many friends have it and anyone who wants to play can get the game for free. Check this awesome trailer for more info but in order to get the full experience I suggest that you download the game and try it, it’s free either way!
Planetside 2 - FPS Big Battles - https://www.planetside2.com
PlanetSide 2 is a Massively Multiplayer first person shooter that delivers truly epic
HAWKEN is a multiplayer first person shooter for PC that places you inside a mechanized war machine on the battlefield of a dystopian world called Illal.
With strategic, fast-paced gameplay, HAWKEN features incredible alien landscapes, customizable and upgradable mechs, and dynamic experiences across multiple competitive game modes. Black Mesa - FPS Based On Half-Life - http://www.blackmesasource.com/
Black Mesa is a re-envisioning of Valve Software’s classic science fiction first person shooter, Half-Life. Powered by Source Engine, You will re-visit the inaugural role of Gordon Freeman and his memorable journey through the Black Mesa Research Facility. Expect detailed environments to explore, a huge cast of characters and experimental weaponry. All-new music, voice acting, choreography and added dialogue give way to a more expansive and immersive experience than ever before. Xonotic - FPS - http://www.xonotic.org/
Xonotic is a free and fast-paced first person shooter for Linux, Mac, and Windows. It combines addictive, arena-style gameplay with rapid movement and a wide array of weapons. Xonotic is available under the permissive GPLv2 license.
Battle for Wesnoth - turn based strategy - http://www.wesnoth.org/
The Battle for Wesnoth is a turn-based tactical strategy game with a high fantasy theme.
Build up a great army, gradually turning raw recruits into hardened veterans. In later games, recall your toughest warriors and form a deadly host whom none can stand against! Choose units from a large pool of specialists, and hand-pick a force with the right strengths to fight well on different terrains against all manner of opposition.
Feel free to comment with your own suggestions in case there were a few good ones I missed! If I like a game I will add it to the list!