Brave Sir Eric, don't mix up the whole of the demogame with the demogame rpg. The actual demogame is indeed some form of SG, but there's a structure which provides a way of decision making. In fact, all participants vote for representatives, and those people do the actual playing of the game. Everybody can participate and everybody can get elected. Each election term is one month, so there are monthly elections.
The demogame rpg is related to the demogame. The participants each take a role, and play that (that's what a rpg is, right?)
Each 'turn chat' (where the 'government' decides what to do), about 2 to 3 a week, you get a certain salary. You can get this salary by signing up for the demogame rpg in the rpg forum.
For more questions, there's a demogame faq, and there's also a rpg faq somewhere buried in the forum. The people there wil gladly help you.