Here you go:
The games listed below all run on Win 7 64-bit (tested personally).
Babo Violent 2
A quick action, top-down shooter.
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OpenTTD
Open source simulation game based on Transport Tycoon Deluxe.
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Hedgewars
Basically, exactly like the classic Worms games, but with hedgehogs instead. I enjoyed this more than WorMUX.
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S.W.I.N.E
Pretty sad that so few people know about this gem. Swine is an RTS title with a few twists. Lots of fun, great multiplayer modes.
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Celestial Impact
Celestial Impact is a team-based multiplayer FPS taking place on asteroids. Landscapes can be deformed.
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BZFlag
A simple first person 3D tank combat game.
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BosWars
A futuristic RTS title that plays much like the current free CnC games.
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TripleA
A turn-based strategy game based on the Axis & Allies boardgame.
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Unknown Horizons
An Anno clone (emphasis on economy and city building), game is still under heavy dev.
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Dark Oberon
An isometric RTS game with all the models and textures created from plasticine.
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Digital Paintball 2
An FPS paintball game built on the Quake 2 engine.
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0 A.D
A high quality open source RTS game of ancient warfare. Very much like Age of Empires. Graphics are superb for a free game.
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Simutrans
Another Transport Tycoon clone. Has some features not in OpenTTD.
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Red Eclipse
A total conversion of the Cube 2: Sauerbraten engine. Players can do movement tricks like parkour, boosts etc. Includes mutators and many game modes.
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Gang Garrison 2
A retro 'demake' of Team Fortress 2. Played in a 2D, 8-bit environment.
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Starfare
Starfare is an RTS where players have to capture asteroids and hold them to gain resources and bring down the enemies. The tricky thing is that the asteroids may not always be static.
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Toblo
A third person CTF game where players can pick up blocks in the environment and throw them at enemies. The game has a full physics system and support for up to 4 players.
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Xonotic
A direct successor to Nexuiz. Wide range of weapons and maps.
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Rise & Fall: Civilisations At War
Midway released the full (add supported) version of this excellent RTS title in 2008. The game features four playable civilizations: Persia, Greece, Egypt, and Rome and incorporates elements of first and third person gameplay where players are able to control a hero unit in battle.
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Zero Ballistics
A fast paced first person tank combat game. Good quality graphics and physics. Four game modes for your enjoyment. Can also be practiced offline with bots.
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Ground Control
Shortly after the release of its sequel, Ground Control was released to the public for free. It is a visually stunning real-time tactics game.
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Installation asks for CD key from FilePlanet. This key is only needed when playing online, you may skip the key retrieval. The game runs normally without it.
ArmA 2 Free
The free version of ArmA 2, things not included are the campaign, HD graphics and support for mods. Custom single- and multiplayer missions can be installed (those that do not need add-ons), lots of multiplayer options and game modes, full armory mode with unlockables.
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Subvein
A fast paced top-down shooter. Players are able to upgrade their characters with many passive and active skills. There are over 20 weapons in the game, lots of maps (user created as well), game modes and vehicles.
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Full Spectrum Warrior
Full Spectrum Warrior was released for free in September 2008. It is a squad based tactical shooter.
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[Win7 64-bit NOT YET CHECKED]
Area 51
Area 51 was released as freeware by the United States Air Force. It is an FPS survival horror game.
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[Win7 64-bit NOT YET CHECKED]
World of Padman
WoP is a curiously fun FPS based on the Quake 3 engine.
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[Win7 64-bit NOT YET CHECKED]
P.S
The Smokin' Guns link gives a 404.