GameSpy
Key points
- All remaining GameSpy services were shut down on May 31, 2014 (June 30, 2014 for Electronic Arts titles).[1][2] This affected matchmaking support for most games using it.
Essential improvements
GameRanger
GameRanger supports many GameSpy games; see GameRanger - Supported Games for a full list.
GameSpy server emulator
One user examined the protocols and setup of GameSpy, detailing his notes here: http://aluigi.altervista.org/papers.htm#distrust
In the set of links includes a server emulator that should function for games like Battlefield 2.
OpenSpy
OpenSpy is an open source clone to GameSpy servers