Well more like way back in 1997 in the great game called Goldeneye 64
I remember playing through the game the first time and thinking wow i saw a door to the left side of that corridor while running from those bad guys. I wonder if i could go through there, is it a shortcut? is it a different exit? Well i'll just have to play that level again to find out.
Turns out those doors or alternate routes sometimes led to places sometimes they did not. And that was part of the fun, trying to find out if there were different ways of completing a level.
Then there were the cheats .If you wanted to unlock them you had to beat levels in a set amount of time. Once you had them, it opened up newer ways of playing do to invincibility, invisibility, all guns, etc, etc.
You could now see what was behind that door before the guard closed it, or just explode that crate where you never had anything to explode it revealing a mysterious item that possibly had more uses but now is only a simple weapon.
(Spoiler for tall tales 9)
My point is, I remember doing tall tales and then running in to the waterfall on the shores of gold, I thought wow is there a way through there somehow, whats up there?
The moment i was in the final cave fighting the final boss i thought, wow that waterfall i wonder what was up there, i'm going to have to play this again just to find out.
To my surprise and disappointment that is the exit of the final cave. And with that the curiosity of the island died out since everything that has interaction is used in the final quest.
Now imagine if there could have been a sneaky way of climbing that waterfall and somehow bypassing the entire cave BUT with this in mind you would be given a slightly different ending and or reward.
Imagine having multiple paths in the cave which ones could be a path to a different boss while the main one was the most rewarding.
Now this is not about changing the game but just adding slight variations that add this "replay" value which is difficult to get just right, otherwise you can end up with a Phantom Pain (which is good, but no where near it's predecessors.)
