Tribute and Vassal States: Introducing New Diplomatic Options

This mod adds two new types of alliances: Tribute States and Vassal States. Each has its own unique method for establishing alliances and distinct alliance effects separate from other forms of alliances. Do you find Civilization VI's diplomacy system too rigid? Why do neighboring civilizations and city-states, often no larger than a small part of your empire, refuse to adopt flexible diplomatic strategies or yield to your superior power? Capturing AI cities is tedious and unrewarding, while widespread warfare damages your global reputation. Some countries might not even match the economy of one of your cities, yet they still stubbornly maintain poor relations with you. Shouldn't your overwhelming economic superiority translate into diplomatic leverage? We will teach these AIs a new world order. Tribute States can be established by moving your unit near another civilization's capital. A "Propose Tribute" button appears on the unit panel, allowing you to establish a tribute relationship by spending five turns' worth of the target civilization's gold income (requires more if your Diplomatic States is bad). There is also an option to offer a gift (specific effects are undecided, possibly acquiring their unique units). Vassal States are formed through war. After meeting peace turn requirements post-war, capture their capital (not necessarily the original one) and use the newly added "Establish Vassal State" operation in the conquered city interface. Return the city and transform the defeated civilization into your vassal. These systems also include interactions with city-states. When your unit approaches a city-state's capital, the "Propose Tribute" button appears. You can offer a gift, costing five turns of the city-state's gold income, to add an envoy to that city-state once per era. Engaging in combat against the suzerain of a city-state (never directly attacking the city-state itself), you gain one envoy in that city-state for every unit killed within its territory.