I've seen a lot of these games, but I couldn't start one. So, the question is:

How they work? How to play them? How to start one?

They do not work. Avoid them like the plague!

They do with good people.

Most diplomacy games give the rules in their initial description. To form the pre-set nations, you generally need to be able to make a custom scenario, which is unlocked at level 47. It generally involves not immediately attacking others, and using alliances, trades, and diplomacy to find a way to make peace. Generally, to attack someone, you must declare war on them in the public chat, or risk becoming Public Enemy. The PE is allowed to be attacked by anyone, without a declaration, and is often required to be attacked. If you want more detailed information, either mail me, or join a diplo game and ask.

Thanks!