

Games like Mass Effect, Tomb Raider have all those animations, and that's not even close to what Assassin's Creed has. FO4 is so simple that you can duck, jump, run, but they don't even have existing animations for ducking behind the wall, leaping over a fence, body dive (through a small window) and roll on the ground. And the animation is going to be a pain to do. Parkour is more than just climbing and vaulting over objects, so there are more complex calcuations that require the game designer to have a much better collision map than what FO4 has. it's a wall (and collision map will tell the game this action is not allowed).

But at a wall, player cannot hit W to go in. At a window frame, player can either go in (hit W to go straight) or jump up (hit Spacebar). Use Assassin's Creed for example, beside the beautiful texture of the world, underneath, there is a map that defines all the objects player character can grab onto and the game decide what kind of actions are allowed to do. To make this happens, the game has to have a very detailed collision map. Because this really involves core design. I am not sure how possible your idea will be.
