it closed down because it became boring after building your army (and some buildings) for the 50th time.
That's why the building part is separate and persistant. You build your lander (base) and landing crew (army) in orbit, and recycle it throughout the game.
You could even further extend this by allowing ground players to offer bounty on ground targets for reward, this could be balanced by saying there is some kind of governing body who adds funds to the bounty of weaker players.
That's a cool idea. I could also add some AI players that add a bounty on the strong players. That way there is always motivation to attack the bigger players. Maybe something like ransom: You "kidnap" an enemy unit, and demand a ransom for it. The strong player is handicapped until the ransom is paid (or until he kills you). Anyhow, a mechanic that adds motivation for attacking strong players sounds good.