As much as I love The Evil Within, the fact that the final boss becomes a scripted sequence of running and shooting it down whenever the game tells you was a tad disappointing. And you have very finite ammo and the game won't give you a second chance if it runs out (nor it immediately gives you a game over, you have to wait for it in a very dumb fashion), so meh.
While I wouldn't call it completely different gameplay because the principle is the same, Ultimecia and her castle in Final Fantasy VIII is relatively a good example. You are stripped away from every combat option you had up to that point (casting magic, reviving people, using abilities, even saving the game!), so you can either hunt down a series of optional bosses that will give you back all these abilities one by one or just go straight to Ultimecia, risking everything since your abilities are locked. Ultimecia herself will put a random party for her combat instead of your usual group (and she tends to put the people you use less, so you are forced using the characters you haven't really given much time to, unless you struck a balance with them), and every time a character of yours is defeated Ultimecia will make them vanish forever, so you can't recover that character by any means either. And the best part is that she will be randomly removing magic from your party at will, so every time you lose some your characters get weaker and weaker. Think of using Guardian Forces to prevent damage from your party? She will instantly kill them and remove them as well so they stop being part of you, crippling your strength and vitality in the process. The core gameplay within the battle is the same as any other, but the way Ultimecia fights you is basically the opposite of how you have been playing up that point.
And I guess we have Fable 2 final boss... just go in front of him and press A for a few seconds. That's it. You can shoot him afterwards a bit or just wait a minute and someone else will shoot him. And that's really it. Final Boss done.