So I made a post over on NeoGAF, in reply to someone suggesting that it was worrisome that Assassin's Creed and Skyrim were cited as sources for Thief's stealth system. The response was pretty well received, and I thought you guys might like a more in-depth look at how sound can make or break a video game experience.
Okay, first off, it's worth noting that while Skyrim's stealth isn't deep, it's also not quite terrible. In part because The Dark Brotherhood stuff in Oblivion and Skyrim was designed by... an ex-Thief guy. Unfortunately, all the mechanics in Skyrim are shallow, by virtue of the game being broad.
More worrisome is that it takes from Metal Gear Solid, which is easily the least of all major stealth franchises, since it's a rudimentary "make sure you're not in line of sight, that they can't hear you running, and just use the camera to cheat around corners. Sometimes you can use distractions."
Thief, you see, is a first-person stealth series. This might not sound important, but it is, for a couple reasons. First, you can't look around walls. You can't cheat like that. So every decision becomes much, much more weighted, right off the bat. Secondly, and more importantly, Thief's single most important stealth element is sound.
People like to point out the light gem, and they're right, visibility was very important to Thief, and nobody really uses light/dark these days (sup, Dishonored, Splinter Cell: Conviction, Deus Ex: Human Revolution, Hitman: Absolution, Metal Gear Solid's various games, and all you lesser stealth franchises out there) with the exception of, what, Mark of the Ninja?
But... sound. That's what really drove stealth.
And level design.
The levels in Thief were puzzles. You'd go into them, you'd be presented with a problem, and it was up to you to use your tools (jumping, mantling, climbing, rope arrows, water arrows, moss arrows, light/dark, etc) to navigate the environment. But, because it was a stealth game, and one you couldn't cheat with to look around corners, it meant all you had was your ears.
Now, this was rather cool: if you walked on marble, you'd sound differently than if you walked on moss. And the enemies were the exact same way. So not only could you figure out where they were, but you could learn what kinds of surfaces you were near. Plus, the enemies would cough, chortle, have conversations, whistle, sneeze, snore, and all sorts of other things. They would let you know where you were.
In other words, sound became a navigational tool, alerting you both to hazards and the material of the space you explored.
You'd walk through a level, simply listening to the space.
Additionally, sound is often considered to be the single most important element of an audiovisual presentation, and one thing games never really quite grasp, and reviewers don't really understand: good sound presentation is vital to an experience because of the way it affects the audience on an emotional experience. Quite a few of the critically acclaimed games that have really bad mechanics sound REALLY GOOD, and a lot of the people praising these games (especially for things like atmosphere), are really praising the sound design.
And that is why Thief is the best stealth series there has ever been, and so far, it appears there ever will be. Because it had the best sound design, and that sound design actually affected the way you played and connected with the game. A third-person stealth game can never be quite so deep, because people will always use their eyes when they can, to cheat their way around corners.
This is also why games like Hitman: Absolution break down: they give you a mechanic to let you SEE the kinds of things you should be HEARING naturally. Then they remove these mechanics in the "purist" modes, but the games were still ultimately designed to be heard. But, of course, the problem's a bit bigger than that: Dishonored, for instance, becomes crazy dumb at times, because the missions are designed for you to navigate with the map markers turned on (which, of course, tends to make you beeline for your goal, and ignore all the juicy side stuff that they've made); so they give hardcore players an option to turn those markers off, but because the missions are designed with map markers in mind... the maps aren't nearly as intuitive, and thus it's simply a lesser, almost annoying experience. I could write an entire rant about how simply saying "you can turn it off" isn't good enough.