In major DIKU-style commercial MMOGs, there are a lot of standard-issue quest types. One of the creative challenges that designers face is how to introduce enough variation in structure or theme with these quests, and every once in a while, they succeed in coming up with a new twist to an old formula. (For example, the Burning Crusade's popular aerial 'bombing runs'.) One type that most games have used extremely sparingly, however, is the timed quest, where a player must complete a task within a specified period or fail the quest.
There are some technical reasons why these kinds of quests might be a bad idea. Nor, from what I can see, are they popular with players, for a variety of reasons. But it seems to me that they also underscore something odd and unsettling about the temporality of most synthetic worlds.
Timed quests pose the same problem that "twitch" elements in a synthetic worlds design pose: they can run afoul of latency issues, make a disconnection or lag into far more infuriating problems than they would be normally. Players of games with save-and-reload are accustomed to having to redo the same sequence of play over and over again, but MMOG players are not. Time is accumulation, and a quest that is difficult to complete because of technical obstacles is bound to create howls of anguish from players. It's also easier to grief other players who may be completing time quests if those quests involve non-instanced targets or environments--a malicious player can just watch for people who are obviously trying to finish the timed quest and harass them.
However, it's also a question of what kind of fiction a timed quest invokes. In a MMOG built around accumulation of resources and experience, all that a timed quest may do is simply dictate the order in which a player completes some of the quests on his or her list--it's rare that such a quest is set with a demanding time limit that constitutes an element of serious difficulty in its own right. But in magic-circle terms, a timed quest ought to be a part of creating drama, of giving the player a sense of narrative urgency.
That's hard to do in a non-dynamic world, for one. If you're racing against the clock to get an antidote to a poisoned NPC and you fail, it takes some of the potency out of the experience when you just reload the quest and try again.
The lack of dynamism is more important on the overall scale of a synthetic world. The narrative experience of urgency in a timed quest synchronizes poorly with a gameworld where players otherwise have all the time in the world to accomplish all the other quests and tasks that lie before them, and a world where other 'emergent' events coming out of player behavior follow still another temporality.
To take the example of Lord of the Rings Online. LOTRO has a series of Epic "storyline" quests that parallel the narrative of The Fellowship of the Ring, often rather cleverly. Accomplishing such a quest occasionally earns the player a short cinematic about where the story of Fellowship is at that moment. But anyone even moderately familiar with the books or films knows that at times, your character has been doing things that would require weeks of fictional in-universe labor within a timeframe of a day or so in the contexts of the books. While Aragorn took Frodo and his companions to Weathertop and onwards to Rivendell, from September 30 to October 24 of the year 3018, my character fought hundreds of orcs and goblins in the Lone Lands, battled barrow-wights on the borders of the Old Forest, visited the home of the Dunadan in northern Eriador, and so on. In that time, my character had time to spare not just for vital missions against the forces of Sauron, but also for the Tolkienesque equivalent of Superman rescuing cats from trees. A timed quest thrown into that temporality is Brechtian: it doesn't so much make the player feel a sense of excitement and urgency as to remind the player of time spent wandering around looking for a dire warg to kill in order to make quota.
Other mainstream MMOGs have similar issues with temporality and simultaneity: World of Warcraft's Burning Crusade expansion, for example, performed a subtle trick with the new races (blood elves and draenei) by situating their early quests in the "past" of the gameworld narrative.
Timed quests would seem to be a way to add challenge to existing MMOGs that would contrast with the normal methods (making quests longer, more mind-numbing or requiring superior equipment), but it's hard to make time flow urgently only on rare occasions. I'm curious about whether TN readers have encountered particularly satisfying (in both game-mechanical and game-fictional) examples of this genre of quest.