Event Driven Vs Player Driven Stories
When playing Hearts Of Iron 4 mods, I always had one big problem. When I do something like declaring a War does it break major event chains? Lets take Kaisereich as an example. It give nations different story paths. The problem is that often the actions of the player can and will break it. The stories are all quite linerar in nature.
Thinking I want to be at war with nation X can break many things when the mod expects to declare a war or peace via an event or a focus tree. The developer needs to account for the possible actions of the player to make it not possible to accidentally softlock the player.
This is the major difference between a player driven story and an event based story.
When I played such mods, I always worried that my actions would break a certain story line I wanted to play. Always searching for a guide. Because I knew that if I didn't do that valuable time could be wasted. After hours I learned that my path was now blocked.
In Europa Universalis IV a similar problem exists with mission trees. If a mission expects a certain nation to exist and the devloper didn't account for a scenario where they dont, the tree gets softlocked.
And again its a story created by others not the player. Taking account for so many variables that could break the story is hard.
Sometimes mod developers for HOI4 even take away player options to restrict them to their story.