Play By Committee SE4 Game.

[Suicide Junkie]

Basically, it will be forum-based.
The System Lords bicker and scheme and trade and roleplay on the forum, then post their orders in a hidden sub-forum during the week. On weekends, I will take those orders, apply them to the game and process the turn, then update the budgets and post the new savegame.

Those players on the interior of the empire will tend to have more political intrigue and resource haggling, while the ones near the borders will have more exploration and combat to deal with.