A single world government?

When playing on this site, I originate most of the games I play, so that then I am red - this way, I can imagine I'm establishing the One World Socialist Republic by revolutionary war.
But then, a couple of days ago, I had a great idea. Why not have a directly-elected parliamentary assembly at the UN - and I mean directly-elected, by the populace of the various countries of the world, not appointed by national governments.
Given that so many supranational institutions have so much power in the world (multinationals, the World Bank/IMF, etc), but are not, or are unfairly, controlled by national governments, shouldn't there be a proper, democratically-elected body that might be able to act as a check on these?
Well, blow me down, if the very next day I didn't discover that loads of other people had had the same idea, and in fact launched a campaign for the UNPA that day.
It's possible that I'm confusing the chain of events here, and that in fact I hadn't given a single thought to the idea of a UNPA until after I'd heard about the campaign...
But then, a couple of days ago, I had a great idea. Why not have a directly-elected parliamentary assembly at the UN - and I mean directly-elected, by the populace of the various countries of the world, not appointed by national governments.
Given that so many supranational institutions have so much power in the world (multinationals, the World Bank/IMF, etc), but are not, or are unfairly, controlled by national governments, shouldn't there be a proper, democratically-elected body that might be able to act as a check on these?
Well, blow me down, if the very next day I didn't discover that loads of other people had had the same idea, and in fact launched a campaign for the UNPA that day.
It's possible that I'm confusing the chain of events here, and that in fact I hadn't given a single thought to the idea of a UNPA until after I'd heard about the campaign...