ReiverCorrupter said:
It actually wouldn't take that much to do; just an afternoon or two in the studio with a motion capture camera. They have to do that anyway. The only rule I would keep in mind is to keep the sequence fluid and under a second in length; any longer than that and the player will be frustrated by the character's unresponsiveness.
Trust me, it would take much longer than that. Maybe if you had everything and everybody ready to go, you could bang out all of your mo-cap sessions for your finishing moves, but it takes a lot more than that to get them in game.
Mo-cap data is a good starting place, but almost never a be-all-end-all. It's never 100% how you want it to be, and always requires the tweaking of additional animators. They could fix everything from smoothing out the animation, and adjusting the timing to make it fit better within a sequence, or even completely reanimate whole parts of it to get to the finished product. Once the data is how they like it, it needs to be brought in game and tested. There could be some back a forth here, more animation tweaking following by trying it out in game, over and over again. Heaven forbid they change a sequence for whatever reason (game design decision, engine change, etc.), then you might have to fix it more, or even scrap it and start all over.
So you have a throat slicing finisher, for one human on another. Now what about other creatures with throats? How about the Minotaurs or Ogres? Now you have a size difference, and most likely they'll all require their own sets of moves. That's even more mo-cap time, another round of animating and tweaking and testing. You also have to debug the crap out of it, to make sure it doesn't 'break' under certain conditions. These could be related to relative size (Nord vs Bosmer), their positions (relative animation sequence and/or world space XYZ coordinates), or any other number of factors that can pop up during development.
It's one of the reasons that all of the NPC's in Oblivion had the same voice. It was such an undertaking to give everyone dialogue, and so much had to be recorded, that even casting a separate VO for each race/gender (20 total), not counting unique NPC's and monsters. You already had hours of recorded dialogue, and it was enough of a feat at the time just to accomplish what they did. But with Bioware pushing the envelope with Mass Effect, Dragon Age, and the soon to be Knights of the Old Republic, they keep pushing forward the expectations for game dialogue. If they can come close, it'll be a feat for a game of this scope.
Ultimately, they just have to be careful to not let their ambitions cause them to over-reach their abilities. I'd love to have a TON of uniques finisher moves, and I'm sure there will be quite a few (they where in Arkane Studio's 'Dark Messiah', and they where awesome back then too). But time and money always put limits on your production (unless you're 3D Realms), and rarely are things ever quick and easy. The amount of work to get anything into a game, and polished to a level worthy of a retail release, is always an undertaking.