Secret House Rules

[eggynack]

Secret houserules do not diminish the impact of one's choices, though, they merely inhibit the ability to unerringly predict what that outcome will be.

I think the player agency thing is a bit of a side-discussion, connected to hidden and changing house rules in that they both break fundamental rules of game design. There is probably a level of disconnect between action and reaction at which player agency becomes somewhat pointless. Those choose your own adventure books are a reasonable example of that sort of thing, I think.