As in, take-up-every-single-second-of-free-time satisfied.
Bethesda took creative leaps, made a kickass world to get lost in, and refined the gameplay nearly to perfection (though I will say that I miss attributes, but whatever). It rightly deserves game of the year. All I miss from Morrowind (and Oblivion through modding) is levitation. I know I could make a mod for it on a PC version, but my computer would never be able to support the game, so I'm stuck with the xbox version.
I know levitation would be a game-breaker; you could just pop on top of the Throat of the World and speak to Paarthuurnax before the greybeards or the blades ever got a chance to say so much as "wazup," but at the same time, I can't help but think there must be some way to implement it.
And I think it could work, but it would need to be a shout, not a spell, called something to the effect of "Dragonwing" (which would be awesome). Fully unlocked, the shout might be no more than 30 seconds, but we'd really appreciate the opportunity for a bit of nostalgia! Flying like a dragon would be something we could all appreciate, even if it is for an amount of time that doesn't break the game.
I dunno, it might still be a game-breaker anyway, but I couldn't resist putting the thought out there. If I saw that in an expansion, my life would be complete.
EDIT: This would be great as a part of a larger expansion, like tribunal or the shivering isles, not DLC in and of itself.
