Hello everyone! After many people have been requesting it, puppet nations are finally in the game! Here's how they work...
Puppet states can form naturally through wars if the defender is in a bad spot after the war. Puppet states will be forced to donate gold to their overlord every few years. You can see when an overlord will require donations in the overlord's Nation Panel. Puppets cannot join alliances, but they can start their own wars. Every time a donation is made, the green Integration bar also gets filled a little. When this reaches full, the overlord can demand territory from their subject. The subject might agree to it, but depending on the situation, power balance and especially if they are about to lose their last territory, they might revolt in an attempt to declare independence. If the war is successful, they will be released.
In normal view puppets will show with a border similar in color to their overlord, and in a purple shade in Diplomatic view. Some things in puppets might change in the future depending on player feedback, but go out there and test them out! Currently puppets cannot be created in scenario editor, but that will come later along with other improvements to the scenario editor. Also, as this is a whole new mechanic, there might be some bugs I haven't noticed. Let me know if you encounter some. In other news, the USA map and scenario have also been remade, now featuring proper terrain and additional cities!

v3.2.0 Full Changelog

Additions

• USA map and scenario have been recreated
• Nations can now form puppet relations with other nations
• Puppets can naturally be formed at the end of wars if the conditions are right
• Puppet nations will give gold to their overlord every few years
• Occasionally puppet masters can demand land from their subjects
• Puppets can declare war on their overlord in an attempt to gain independence
• In normal view puppets' border is the same color as their overlord, and they will have a puppet icon next to their capital
• Puppet nations show up in a striped pattern in the Alliance view if their overlord is in an alliance
• Puppet creation, land seizing, and puppet revolts can individually be turned off in AI Settings
• Puppets can be manually created and released through the Actions Panel
• Text popups relating to puppet actions can be toggled on/off