Just so you're aware, we DO have a map editor that we will be releasing in the near future. It is our in-house development tool, so it doesn't have a lot of bells and whistles, but it let's you fully create space and ground maps. In addition, Supremacy already has built-in support for synchronizing maps between players -- so if you connect to someone with a custom map, it will show up in your game list (and you can play on it). You don't have to email/post your maps for others to play them!
Give us a few days, and I'll push the higher-ups to get the tool posted.
- Vance Vagell
Programmer
Black Hammer Game
www.supremacygame.com