Battlefield 1942 is still very much alive, you can still get it for free. EA made this game free to play in 2012. The new master server is

OpenRA is a Free Real Time Strategy project that recreates the classic Command & Conquer titles.

Open Arena
OpenArena is a community-produced deathmatch FPS based on GPL idTech3 technology

UltraStar Deluxe is a free OpenSource karaoke game for your PC. The gameplay experience is similar to that of commercial product SingStar

Game Downloader is a small open source download client with a server side library of games that are open source, indie or freeware.

Age of Defenders adds a colossal new twist on the much loved tower defense games, whereas, you not only defend your base but you attack too!

Racing game.

Battlefield Play4Free
If you ever played Battlefield 2 then you’ll instantly find Battlefield Play4Free familiar. Play4Free is essentially a reboot of Battlefield 2, except it runs in your browser and looks slightly better.

is a 3D real-time strategy game.

Turn-based tactical strategy game with a high fantasy theme.

Racing game.

Racing game.

First person shooter.

Civilization in your browser

Flash games

is an Arena First Person shooter.