One of the best variants I've played is this No treasury . You aren't allowed to have a treasury, so every deal has to be based on income. This makes your reputation extremely important and doesn't allow things like min science. We played it twice and it can be a very difficult variant. As can be shown in the first failed attempt, which is linked in the first post of my example. Nad has had more brilliant ideas, like this one: Chamber of Secrets. I don't know how to call such a variant, but basically we had to stick to the rule '25 turns of peace / 25 turns of war, without restrictions.' PS. Your sample game of an OCCC allowed cities during the turns. So this is the easier variant of an OCCC. You can demand cities for peace and abandon them, conquer cities and keep them until the end of the turn. The most obvious advantage is the opportunity of building armies.