1. Battle For Wesnoth
Turn-based strategy game with a fantasy theme. Highly touted FREE game
2. Enigma

Uncover pairs of identically colored Oxyd stones while solving puzzles - addicting

3. Neverball
Miniature golf and an obstacle course
4. Sokoban
Sokoban is a maddeningly simple game. The word Sokoban means "warehouse keeper." The object of the game is to put all of the crates in your "warehouse" into the designated storage areas. Sounds easy, right?
5. Hot Potato Online
Think dodgeball with a grenade! FUN!
6. America's Army: Special Forces (2.6)
America's Army provides players with the most authentic military experience available, from exploring the development of soldiers in individual and collective training to their deployment in simulated missions
7. F.E.A.R. Combat
Take a first person shooter, spice it up with a generous helping of survival horror elements, and you get F.E.A.R. Get your unique key at http://www.joinfear.com/main?act=register1
8. Soldier Front
Soldier Front is a 3D FPS, focused on the hardcore gamers. Soldier Front offers a totally new type of FPS. Soldier Front offers realistic game play and graphics, but also offer a character growth system allowing gamers to retain their stats and rise through the ranks like a real soldier. Soldier Front is the next step in FPS gaming.
9. America's Army: Special Forces (Overmatch)
America's Army, the official U.S. Army game, is an innovative PC action game that provides civilians with an inside perspective and a role in today's modern Army. America's Army provides players a virtual portal into the Army, ranging from exploring the development of Soldiers in individual and collective training to their employment in simulated missions in the Global War on Terrorism.
Online manual: click here
10. America's Army: Overmatch patches/maps
Highly recommended addition to America's Army: SF (Coalition) Full game:
These new missions were made in conjunction with the America's Army Development Team in Emeryville, California. The students used the Mission Editor that was released with AA v2.8 (Coalition) and utilized existing game assets for their maps.
11. Americ's Army : Mission Depot
This site gives members of the America's Army community, the unique opportunity using the America's Army Mission Editor to create and submit their own maps. Those deemed "Mission Ready", will be deployed for play on Honor Servers. So get to work soldier... By this point you won't be able to believe this is a free game!
12. Orbitz games Collection of quick and easy Flash games that can be played online.