WeeBot is a .NET framework for hosting bots and testing game modifications to the Weewar online TBS game (weewar.com). It provides APIs for bot development as well as a client and single game server for hosting and testing bots offline.
Game-Tracker is a game server browser written in C# for the .NET platform with the goal of being a powerful, fast, full-featured game server browser and administration tool. Official homesite at http://www.game-tracker.com/ .
Diablo 2 Closed Game Server. The project was orginally developed inhouse by Net-Games (www.net-games.com), and has been made opensource for development speed up and getting new features built in.