GameRanger
GameRanger is a free download for Mac and PC that lets you play over 600 games and demos online with friends and opponents worldwide.
Drop-in replacement and upgrade for the legacy GameSpy network, thus no user client needed to connect or play.
a direct "like for like" replacement for the gamespy masterserver, and supports a huge number of games.333networks is the official masterserver for several games companies, and can be selfhosted, or use the main master, or both.
most alternatives require that players and admin install and run a 3rd party client which may conflict with other clients (especially steam), and signup to a web site.333networks masterserver uses the original system built into the games, so people see the server lists where they originally appeared.players and server admin only need to change some lines in their game configuration files.hardcoded games can be updated by the game authors upon request, or redirecting the gamespy url to 333networks in a modified hosts file.
Official Website
Source
Facebook
Network Monitoring Multiplayer
network-monitoring multiplayer monitoring networking game-database game-server-browser masterserver