: A custom mechanic for handling large-scale civil wars.
The content related to likely refers to historical versions of the popular A Game of Thrones total conversion mod for Crusader Kings II . While the mod eventually progressed to version 2.2 and beyond, version 0.6.1 and 1.6.1 were major milestones in its development. Core Mod Features Agot Ck2 6.1
If you are looking for specifically "6.1" content, it likely pertains to these releases: : A custom mechanic for handling large-scale civil wars
: Allows players to start at various points in history, such as Aegon's Conquest, the Dance of Dragons, or Robert's Rebellion. such as Aegon's Conquest