Armored Legion

Armored Legion is a free 3D mech MMORPG that takes place all within your browser without large clients to download.
Explore an entire galaxy gaining experience defeating your enemies while earning fame and fortune! Optional turn based combat or real time combat option depending if you are alone or in a group! Create your own military guild units with your friends and gain access to new and more powerful weapons and mechs! Procedural world generation and dynamic time of day for truly unique locations. No registration required!
Genre: MMORPG
Official Site: http://www.armoredlegion.com/


RuneScape
RuneScape is a Java-based MMORPG with some degree of 3D rendering and takes place in the fantasy-themed realm of Gielinor, which is divided into several different kingdoms, regions, and cities.Players can travel throughout Gielinor on foot, by using magical teleportation spells and devices, or mechanical means of transportation. Runescape also has over 136 million accounts created.
Genre: MMORPG
Official Site: http://www.runescape.com/


SherwoodThe Defend your honor in combat and meet players from around the world in an 3D infinitely deep dungeon filled with monsters and treasure. Sherwood Dungeon requires Shockwave.
Genre: MMORPG
Official Site: http://www.maidmarian.com/SherwoodLanding.htm


Moondo

Moondo is a online universe of 3d multiplayer action games to play in you browser.
Create your own Moondo character and customize it as you see fit. Your character will persist across all Moondo games, grow in power and gain cool items on his or her way to become champion of the Moondo, fast paced, cross-gaming universe.
Moondo currently offers four games: Shooting, Racing, Tactics and Sports, all taking place on a youthful and colourful futuristic moon.
Official Site: http://www.moondo.com


Bang! Howdy

Bang! Howdy is an multiplayer online strategy game revolving around the "Wild West". There is no cost to download the game (or to play it in-browser) and start playing.
Create your character then take part in the Gold Rush and other game scenarios in the wacky Wild West!
Genre: Strategy
Official Site: http://www.banghowdy.com/


Call of the Kings

Call of the Kings is a 3d Real Time Strategy game that focuses on Player vs Player combat. Unlike classic RTS games the RTS element is applied to army movement, espionage, diplomacy and estate improvement and not tactical troop movements and resource gathering. You might say that the game style is closer to computer games like Civilization, Heroes of Might and Magic and board games like Stratego and Junta than RTS games like Command and Conquer or Warcraft.
Status: Closed Beta
Genre: Strategy
Fee: You can play the first 5 out of 6 episodes of the game for FREE using a Roamer Account.
Official site: http://www.callofthekings.com/


Quake Live

Quake Live (formerly known as Quake Zero) is a first-person shooter video game project from id Software. Focusing on the multiplayer aspect of the game, so as to nudge the game into succeeding its predecessor Quake III Arena as a "major league" FPS eSports competition game. Available only through a web browser.
Status: Open Beta
Genre: Shooter
Official Website: http://www.quakelive.com/


Pirate Galaxy

Pirate Galaxy is a 3d free-to-play massively multiplayer online game with high definition landscapes and stunning visual effects. You can equip and modify starships to your individual taste and explore the vast game universe with hundreds of stars and planets. Pirate Galaxy can be played directly from your web browser. You don't need to install a client (although you can if you want to).
Status: CLOSED BETA - This means that access to the game is limited to selected individuals and groups.
Genre: Shooter
Official Site: http://www.pirategalaxy.com


Rasterwerks
Multiplayer first-person shooter in your web browser. (It is a pretty amusing quake style FPS game)
Genre: Shooter
Official Site: http://www2.rasterwerks.com/


Battlemail Kung-Fu

BattleMail is a social gaming site, a place where you can challenge your online friends to a variety of games which then turn into stunning 3D animations as your avatars battle each other in a 3D world.
Genre: Social
Official Site: http://BattlemailKungfu.com


SmallWorlds

SmallWorlds is a 3D virtual world that runs inside your web browser. It enables you to build your own room, house, or even your own world, and fill it with a wide variety of items and fun activities.
Genre: Social
Status: Beta
Official Site: http://www.smallworlds.com


Power Football


Power Football is a massively multiplayer web game where you control your players in real-time 3D just like FIFA or Pro evolution.Experience the true power of football when Power Football sets new standards in graphical realism on web games today. Thousands of players enter this football world by creating their own unique football team. Challenge each other, take control over the evolvement of your team and compete about being the best player in the game.
Genre: Simulation
Status: F2P/P2P for additional features
Official website: http://powerchallenge.com/


Action League
Fast and action filled passes from man to man!
In animated 3-D optics you are playing right in the middle of your team. In real-time games against thousands of real opponents or against the computer (AI) itself. Keep all the game situations in view: camera change, perfect game passes – you control everything from the keyboard!
Genre: Simulation
Official website: http://us.bigpoint.com/games/actionliga/


ManagerZone
ManagerZone is a gigantic multiplayer game that allows thousands of users to engage in an interactive manager world.
You run your team with your browser or your mobile phone. League matches are played twice a week and you can at any time adjust the handling of the team. Challenge your friends, top teams, play cups or chat with them and many others in the forum.
Are you ready to become the best Manager?
Genre: Simulation
Official website: http://managerzone.com/


Mojo Drift
The only underwater racing game on the planet. Outsmart your opponents, use funny items and win that Mojo Cup.
In this underwater game you have to race against other characters in different environments. Every level has its own difficulties and options. The trick is to push the others from the track or throw things against their heads. The problem is that the other characters will try to do the same with you! You control your character with the arrow keys and two additional keys for turbo and throwing things.
Do you have what it takes to become the new rightful owner of the Golden Snail?
Genre: Racing (3D)
Official Site: http://www.mojodrift.com/