I have some ideas for game mechanic changes:
- Surprise war buff: Lower the number of turns where you can Make peace after starting a Surprise war. A simple situational buff, if you declare a war that has not much reason to back it up, you suffer more penalty of course. But you also have easier time backing off from it, since there is no formal reason for you to be committed in it. Against a human player, this buff might not be as meaningful, since if someone declare a Surprise war and fails to gain such advantage that his opponent wants to end war early, then his opponent will just hold on to the war, play defensively to cripple the former's economy.
- Declare Victorious & Admit Defeat: In Make peace deal, the options to Declare Victorious and Admit Defeat will be added to each side (not required for Make peace deal), along with other deal items. The two options are semi-independent: If one side Declare Victorious and the other side does not Admit Defeat, the Make peace deal can still come through. Both side can Declare Victorious in a war. A side may Admit defeat without the other side Declare Victory. However, 2 sides cannot both Admit Defeat.
Effect:
+A side can choose to Admit Defeat, taking 20% more Warmonger penalty and 20% more War weariness; but against an AI, this will improve its friendliness with the player Admitting defeat. Also, trade routes toward the former opponent's cities gain bonus yield (maybe Gold and Production) (This bonus could be made to yield even more bonus depending on the type of Casus Belli of the war 2 players engaged in earlier: +Faith for Holy War, +Science for Colonial War, +Culture for Territorial Expansion War, etc.)
+A side can choose to Declare Victorious when ending a war, recovering 30% Base War weariness (calculated before other modifiers) and instantly gaining 30 Loyalty to all of his cities; but against an AI, this also worsen its friendliness with the player Declaring victorious. Trade routes toward an ally's city and internal trade routes gain bonus yield.
*For some Casus Belli or Emergency war, Declare Victorious is only possible when at least 1 goal was obtained (For Emergency, it is only possible when the Emergency was successful for you. For Casus Belli: Victorious Reconquest war,Liberation war or Protectorate war can only be declared when at least one valid city of the sort was liberated. Victorious War of Territorial Expansion, Colonial War, Holy War can only be declared when you captured at least 1 city. The Defender, or the one got declared a Casus Belli, may end the war and Declare Victorious at anytime. Etc..)
++ Declaring Victorious has no effect when both side Declare victorious. But it is still there, in case you want to worsen the relationship between you and an AI.
++ Declaring Victorious has amplified effect when the other side also Admit Defeat in the Make peace deal, recovering 90% Base War weariness (Yes, this may result in a surplus in Amenity) and gaining 90 Loyalty.
Declaring Victorious and Admitting Defeat are part of the Make peace trade deal, so no one can declare them without the other's agreement. Players have to pressure the opponent enough to make them agree to Admit defeat or Declare Victorious. Both side can Declare Victorious, but neither would gain any bonus for that, to prevent abuse for online players.
I am not a good modder, but this might need an evaluation value for the AI to use the declaration.
- Economic Victory: A new victory condition, comes along with some re haul to Gold value. As said by John Adams 1826: “There are two ways to conquer and enslave a nation. One is by the sword. The other is by debt.” Players obtain Economic Victory by having their Gold reserve higher than or equal to 33% of the whole world, and retaining that position for a few turns (a nation's Gold reserve = Gold value for that nation * amount of Gold it has). This is not well thought out yet, and I'd need to research more into macro economy to refine the concepts.
Basically, Gold does not have the same value for all players, but rather depends on the player's total Production yield, total Gold yield, out going trade routes, incoming trade routes, resources, districts, buildings ... (international trade routes changes your Gold value based on the receiving civilization's Gold reserve, so war can cripple a civ's Gold value, and thus, its economy). Gold value will be checked for changes every 3-5 turns. Value of Gold in trade deals are not equal for both side, but the AI can calculate it. You can also intentionally cause "inflation" to lower your Gold value, thus lower the amount of gold you have to pay through trade deals (Germany after WW2 inflated their Mark in order to pay for reparations). The actual cost for maintenance, unit & building purchases are always the same. In the menu, costs are displayed in term of your own current Gold value, and will scale up if your Gold value reduces, or scale down if your Gold value increases.
It is an idea I am still working on, but I hope it sounds interesting and not too complicated.