Global Agenda

Free to play MMOTPS with some mild RPG elements. Features single player content to level 15 or so, then requires you to team up with other players to progress beyond that point. There is PvE in the form of 4-man missions that consist of fighting your way to a boss and defeating it; and goal oriented PvP including modes similar to capture the flag (in this case, a robot you must get inside and drive to your spawn without getting destroyed), capture/hold control points, and payload, which is similar to control point but the point slowly moves along a track.

There are 4 classes, Assault (Heavy DPS/Tank), Recon (Stealth and Ranged DPS), Robotics (Pet DPS and Support) and Medic (Healing and light/moderate Poison DPS). These classes can be improved with skill points, earned every other level (to a max of 13), which are placed in one of the three skill-trees available to your class.

As of July 2011 the level cap is 50, but as with any MMOG, that can change later. Supports standard WADS + Mouse control scheme as well as controllers (although menus require mouse control).

Available through Steam for free, also as a stand alone download from the developer's website.

Global Agenda is an awesome MMOTPS that requires teamwork to succeed and is a lot of fun.

MMOTPS

Massively Multiplayer Online Third Person Shooter.

Basically, same thing as a FPS (First Person Shooter) except for the fact that the camera sits behind you instead of in your head looking out your characters eye's.

While games like Gears of War or Army of Two are third person shooters, and have some online play, they are not technically MMOTPS's.

Global Agenda is a MMOTPS.