Argonath already has a govt. though there is a different word for it
i personally dont like the idea of collecting taxes, it will be unfair to new players as Skirmant said.
I niether like the idea of assassinating the govt and taking over, if someone wants to be in the govt. he should prove to be worth it, deserving candidates will be surely selected.
The developers can take care of the ownership of places.......the developers are the government
