A home-brewed, Windows client to facilitate asynchronous / play-by-email style play without the need to run a server.

• multiplayerrobot.com
• JavaGMR - Java, multiplatform version.
• Yet Another Giant Multiplayer Robot Client - Another multiplatform client. Not sure how ready it is.
• https://github.com/intermaxim/GMR-PyTerminalClient - CLI thing.