I never played Planetarium, but I did play a clone - I think it was called Startopia or somet.
I had the most fun time. I was stuck in a system with a bunch of morons, while my friend managed to get one with a powerful alliance. As such, we decided we would see how long it would take for the folk in my system to catch on that I was betraying them. I would tell my ally when people's fleets were away so his people would attack, I'd be defended by him, I would persuade my folk to launch suicide missions.
And the thing is, they never did suspect me. I even got made part of the governing body! Eventually, as the round drew to an end we decided we better do something big, and as such I launched a full scale military coup, figuring
that would get their attention. Some folk even joined with me, triggering a civil war. We were devestated.
Actually no, the last laugh was on me. As the civil war took hold, I used my position as part of the government to delete any messages on the chat system that announced my revolution, and flatly denied any part in it.
Despite the fact I had clearly launched attacks and openly declared my backstabbings, they forgave me, and claimed it was their fault for the misunderstanding 
Don't think I played again. Too many good memories from that one game.
