Although I don't know if they should be playable, the way I'd like to see the Papal states is like this:
In the beginning of your turn, you start with let's say 15 points. Each point can be used in one of the following ways:
- Stabilizing: give one of the catholic states stability points, which will last 5 turns. 1 point could be 1 stability point. One civ can never have more than 20 Papal stability points.
- Provide a special unit: This costs 5 points and may only me done to three civs at the same time. This unit should be a defensive unit, or an attacking unit (crusades). If 2 catholic civs are at war with each other, only one of them may use the unit. The unit may be trained 5 turns, and 5 units are given for free. Free units will be gone after 5 turns.
- Claim a holy city: 15 points. This can only be done once in 15 turns. The city receives a gold bonus (10 gold) and some culture. The receiver has to be Friendly to the Pope.
- Spread hope: A starving, unhappy or sick city receives 2 happiness points, 2 health point or some food. This can only be done in 1 city per 5 the receiving empire has.
- Now, let's get to some real action: war! Whenever the Pope thinks that it's time, a crusade can be started. They can only be started between 1100 and 1350 AD (inaccurate I know, but this shoulnd't be skipped). It costs 15 points, and the next 7 turns you can't spend points, except to help the crusaades. "Official" crusades last 7 turns, but civs may decide to continue, if they do they receive 5 special Papal points. During the crusades, 5 knights are distributed among the crusaders. Crusades can only happen 3 times per game.
(- Release a vassal: Vassals are stimulated to break free. They receive special units, and 1 extra production per tile like in a GA. City defense is also 25% higher than usual.) Costs 15 points and cannot be done more than once per vassal-master deal (for example, if Hungary is Austria's master, the Pope can release Austria, but if they vassalize again he cannot).
- Assign a city: Can only be done once in 3 turns, receiver may refuse. Also, a single civ cannot get more than 2 cities every 15 turns. Receiving or losing cities is free of stability penalties. Costs are 10 points.
- View catholic cities: the Pope acts like a spy and can see all cities owned by one catholic civ for 3 turns. Costs are 3 points.
- Anything else? I'd rather leave out destructive opportunities, as they can ruin the game.
(- Save points for later (maximum of 50 points). If so, some values should be changed.)
Of course, you won't be doing this every turn if you don't want to. There will be a bonus, even a victory that's designed to make sure that the player will use it's abilities.
I know that it's a bit late to discuss everything again, and I like the previous ideas, and I know that lots of it have been decided already. I've tried to give some real action to the Papal States, that may be fun even if they are not playable. Also, it adds some replayability, as the pope can decide to help a really weak or very powerful civ, that can be turned into the world power that the world has never seen before (Lone Wolf, are you reading this?
) So, what do you think of it?