Since Blockland runs on the Torque Game Engine, I've decided to check out the source code for the engine. As it turns out, TGE provided networking code, scripting, in-engine world editing, and GUI creation. The source code could be compiled for not only to Windows, Macintosh, and Linux; but also Wii, Xbox 360, and mobile platforms due to it's easily compatibility with the other platforms. (No I'm not a developer of Blockland)