The purpose of this page is to document all the requirements to trigger the completion of the game. Unless explicitly mentioned, requirement here means hard-locked requirements, and not physical limitations that may try to prevent early access to events.
For example, Concubine fights in palace rooms have a physical limitation that you need both the blue plate and the yellow plate unlocked for traversal. However you can trigger the fights if you find a way to reach them without the plates. On the contrary, even if you found a way to reach the top of inner temple, you cannot finish off Ahriman without triggering certain events prior to it.
The game is divided in three acts. Currently there are no known ways to trigger events from a different act from the current act. The end goal of each act is to trigger the specific event that trigger the next act, or finish the game.
PS: This is not a naming convention that we made up, we can see this by doing some reverse engineering on the forge files using AC Viewer.