Endless Legend - Vassals

In order to improve multiplayer functionality for groups of friends playing Endless Legend together i recommend the following mechanic dubbed "Vassals."

The current issue:

Defeating an enemy Player-Nation in multiplayer forces the defeated player to leave the game, thus preventing them continuing to contribute to the game or continue playing until the game ends.

For this unfortunate player he is unable to continue playing with his friends.

What i recommend:

Upon claiming the last Player-Nation city, or upon surrender diplomatic action (A demand sent by the enemy player) the defeated player becomes a "Vassal" instead of being ejected from the game.

Vassal Cities are permanently allied with their Ruling Nation and follow Alliance mechanics, the difference is that Vassals may not use controlled-neutral armies to attack their Ruling Nation.

Furthermore for the remainder of the game, the Vassal can only win if their Ruling Nation wins, thus promoting them to work with their Ruling Nation to achieve victory while also allowing said player to continue participating in the game.

If the Vassal player leaves the game all their belongings become AI controlled or are transfered to the Ruling Nation by choice of the Ruling Nation (Pop up notification).

Thoughts, suggestions and comments are welcomed and recommended!