(2006) - Racing
GT HD Concept was originally set for a retail release, Polyphony decided to scrap it and instead work on Gran Turismo 5. It is now available as a free download thru PlayStation Network, with 20 cars and one track, and with 1080p 60fps graphics.
(1994) - Role-Playing Game
The floppy disk version of Arena was released as freeware to promote Oblivion. You can download this small file for free at this website, but may need DOSBox emulator to run it properly.
From the same development team behind 'The DinoHunters' comes this History Channel sponsored series of 'episodic' games which are designed for people to experience and learn more about history's greatest battles such as 'Battle of the Bulge' and 'Iwo Jima'. As with DinoHunters, these games are also based on Valve's Source engine.
The original America's Army, sometimes called 'America's Army: Operations', launched on July 4th, 2002. Based on the UnrealEngine2, and free to download, it takes people through realistic offline training levels before you are allowed to log on for their free multi-player. Team tactics, authentic weaponry, and standard military practices are what this FPS shoots for.
It was launched by the U.S. Army as a means to promote themselves, and to act as a strong recruiting tool aimed at the 'gaming' generation.
After the source code for the hit classic 'Star Control 2' was released, this open-source project began to develop a polished improved version of SC2, designed to run on new PC hardware and operating systems.
Half-Life: Decay is an extra campaign (with co-op play) that was only released on the PS2 port of Half-Life. With the help of the Source engine, it has been re-created by Ukrainian developers as a free add-on for Half-Life.
Unlike the weak 'Half-Life: Source' that Valve included in their Half-Life 2 game, Black Mesa is a fan-made complete conversion of the original 'Half-Life', also built on the source engine, but this time with all textures and levels re-built from scratch using Half-Life 2 modding tools.
As of beginning of 2008, it is not yet released, and even though technically 'free', may require a valid Half-Life 2 steam account before you can download and play it.