In Patch 0.4, I've given NPCs the capability to declare war - on players and on each other. This actually completely revamps how warfare works.
In previous patches, NPC provinces are passive - they do not declare wars at all. And the warfare is player-centric and only works for the attacker. In this patch, we need a new warfare system that treat the player and NPCs equally and works for different war participants (lead attacker/defender and co-attacker/defender)
Changes to War Participation
In previous patches, co-attackers/defenders join and leave automatically based on conditions. For example, if the defender manages to get a new ally after the war, that ally will join the current war. This is no longer the case in Patch 0.4. The maximum war participants are fixed once the war is declared. New allies won't be pulled into wars automatically.
Leaving War Coalition
Co-attackers/co-defenders can also leave the war coalition after one year - this costs diplomatic points and will result in a temporary negative attitude from the leader of the coalition (lead attacker/defender).
Changes to Truce Length
In previous patches, the truce has a fixed 5-year term. In Patch 0.4, the length of the truce is the same as the length of the war - if the war lasts for 3 years, the truce will last 3 years as well. Co-attackers/defenders leaving the war coalition will not enforce a truce.
When NPC Declares War
When an NPC province declares war on you, you will get an event popup with details. There is also a separate tab on the right to keep track of the war.
The war will end up in two scenarios. When the enemy achieves enough war score, they will conquer the war goal and a truce will be enforced. In this case, you will cede land to your opponent - but you will also get a "Reconquista" casus belli, which has a special effect that tiles originally owned by you contribute 50% less to War Score.
When your war power is so great that the enemy is not expected to win, or the war is so long that the enemy doesn't have enough internal stability, a white peace will be negotiated - the status quo is restored and a truce is enforced.
This hasn't changed much from the existing warfare mechanism - just so that you can now be on the defending side as well.
When You Get Pulled Into a War
Sometimes you get pulled into a war between NPCs due to your diplomatic treaty with one side. In this case, you will also get a popup with details, and progress can be viewed on the right side.
As mentioned previously, you can leave the war coalition after a year of the war, resulting in an attitude penalty from your ally. If you decide to stick to the end of the war, you will get a popup showing the result.
NPC Warfare
Currently NPC runs a simple yet effective handcrafted war logic. It brings the world "alive" - and every run is different. I've run an NPC warfare simulation, and here's a time-lapse video.
Of course, I will keep improving the logic going forward, but the current one is already a solid foundation.
With all the NPC wars, I've also added a new war tooltip that helps keep track of ongoing wars at a glance.
Diplomats Reworked
In previous patches, a diplomat is used for an action - if you want to improve relations, infiltrate and form an alliance with a province, you will need 3 diplomats. In this patch, only one diplomat is needed. A diplomat can be stationed in a province, which can be used for multiple diplomatic actions.
More Dynamic Diplomacy
In this patch, the duration of a diplomatic treaty (alliance, defense pact, etc) has been reduced from 50 years to 10 years. Sabotaging a treaty will now prevent a province from forming new diplomatic treaty for 10 years (down from 50 years) and now only requires 60 infiltration (down from 150). This will make the diplomatic situation more "dynamic" - so you should pay attention to it!
Social Class Dissent Reworked
One feedback from playtesters is that social class dissent is hard to manage. In this patch, social class dissent is no longer clamped - it can go from negative to positive. When a class' loyalty is higher than influence, you will accumulate negative dissent, which creates a buffer when later on loyalty starts to dwindle and dissent starts to rise. And when loyalty is equal to influence, the dissent will drift towards neutral (0).
The penalty for a social class dissent is also reduced from -25% land tax, goods tax, manpower, and -25% stability to -10%/-10.
Demand Tile/Tribute Now Uses Coalition Prestige
In previous patches, when you demand a tile or tribute from another province, the acceptance chance is based on the prestige between you and that province. In this patch, it is changed to take your diplomatic treaties into consideration. The participation rule (i.e. whether an ally will be part of the coalition) is the same as declaring a war, but instead of using war power, prestige is used to calculate the chance.
Tile Autonomy
Sometimes when you conquer a new tile, due to different cultures, religions, or other reasons, that tile's unrest is hard to bring under control - and that tile keeps having rebellions. In this patch, a new mechanism called "tile autonomy" is added - each point of autonomy reduces tile unrest by 1, and reduces tile land tax, goods tax, and manpower by 1%.
This patch also includes a bunch of bugfixes and QoL improvements. For example, you can now use the + and - keys to quickly adjust game speed - and I plan to introduce a rebindable hotkey system in a later patch. This patch is not compatible with previous save files - the game should prompt you to reset in this case.