America's Army is a free multiplayer first-person shooter computer game released by the U.S. Army as an aid in recruiting and public relations. It is based on the Unreal Warfare/Unreal II game engine. Some debate has sparked surrounding the fact that the game is paid for by tax dollars.
The game is very much like Rainbow 6. Since it has a focus on realism, as opposed to unrealistic "arcade" style, it falls into the subgenre of tactical shooter. It sports such features as bullets go through wood (also doors), bullet ricochets, bleeding from open wounds, and teamwork.
Some may find it annoying, but realism dictates that your chance of hitting the target is greatly diminished when standing and near zero when walking. Grenades are also very dangerous. Your accuracy is also affected by damage, but is slightly increased again when healed by a field medic.
The second version of the game, America's Army: Special Forces was released November 6th, 2003. It is available for Mac OS X, Microsoft Windows, and Linux.