This would seem appropriate to me, too. Roll some opposed checks / a skill challenge to see if you catch him. There are different methods, but I'm with you in the basic concept of using the mechanics to solve it.
OK, but now you have given me the crack into which I wedge my narrativist agenda! (Well, I'm not sure from your other posts on this thread exactly how you run this sort of issue in your game, so I'm not actually sure if I'm wedging you, agreeing with you, or just saying how I'd do it in my game.)
Suppose a player says "I take the shortest route through the town". If anything is actually at stake in the relevant episode of play, then the GM won't just condede this - s/he will call for a check (let's say a Streetwise check).
In [MENTION=762]Mort[/MENTION]'s example, it is the
GM who has had the NPC try and take the shortest route through town. But something is at stake - the PC's want to stop the NPC! So the GM has to make a Streetwise check for his/her NPC, just as a player would. And the players can also make a check, and then the results compared.
Or, in 4e which prefers to have only the players make rolls in this sort of situation (the GM gets no rolls in a skill challenge) then the NPC takes the shortest route and escapes only if the players fail the skill challenge.
So for me it's not about fudging the map, it's about the GM not having authority, any more than the players do, to stipulate that his/her NPC succeeds in some contested action without having to engage the action resolution mechanics.
As I think I posted upthread, or perhaps on the original thread, for me this is no different from the fact that the GM can't just stipulate that his/her NPCs strike killing blows. The action resolution mechanics must be engaged.
Only if such a pass and a route more direct but less travelled to it exist. Otherwise, it is pretty unreasonable.
What I think is unreasonable is the GM letting his/her NPCs autowin when the players have a contrary stake in the conflict.
I too enjoy it in systems that are designed for and around it. Throwing it into games that aren't... I've got mixed feelings on.
As I've explained it above, a fair bit of what in this thread seems to be labelled as "player narrative control", I would be inclined to bring under the heading of "how do the action resolution mechanics handle the range of conflicts that the game may throw up?". If the game is going to make chases an important issue, it probably needs mechanics to resolve them. An example is the evasion mechanics in classic D&D - the players cannot escape an encounter just by specifying "We flee faster than the monsters in a straight line". The players can formulate this intention, but whether they realise it is determined via the mechanics. As I've set out earlier in this post, I think the chase of the NPC through the town should be handled the same sort of way.
The question of whether there is a town less than 20 miles away, or a ford, is a slightly different issue. This
is closer to a genuine example of narrative control, I think, and the blog that LostSoul linked to becomes relevant:
In a scenario in which the aim is for the players to survive the 20 mile journey to town, then letting the players circumvent the challenge by positing a ford is coming close to letting the players define the parameters of their own challenge, which can lead to unsatisfying play. On the other hand, when the journey to town is a challenge, but surviving a 20 mile journey is neither here nor there, then finding and using the ford makes sense as part of the challenge resolution. I think this becomes about a GM making decisions about the parameters of the situation, making them clear to the players, and then adjudicating action resolution (including skill tests that "create new facts", like BW -wises, or the knowledge check that [MENTION=22779]Hussar[/MENTION] suggests upthread) in light of that.
First, if it comes down to DM decision it is in fact "Mother may I"... you are asking the DM whether something exists and it boils down to his decision.
I think there is a difference between clear, even hard(-ish), scene-framing and "mother may I" - one happens before action resolution begins, the other is an unsatisfactory form of action resolution.
I'm not saying I can clearly
articulate this difference, but I think it is pretty noticeable in play, because in the first case you'll have enthusiastic players taking up your challenges, whereas in the second case you'll have grumpy players complaining about your railroading. (If I did try and articulate it, I would say that scene framing creates a "space" in which the players can pursue their goals via the action resolution mechanics, whereas "mother may I" is the players having to beg the GM to succeed in the pursuit of their goals.)
Using an example many of us may be familiar with... un-eratta'd Come and Get It. It was considered narrative control because there was no DM discretion or mechanical uncertainty in it's changing of the narrative. No save, no DM veto power, none of that. That IMO is an example of narrative control given over to players.
I would say that Come and Get It is especially mild narrative control, because its parameters and limitations are clearly specified and inherent with the mechanic.
The complaints I've seen about Come and Get It tend to relate to fictional positioning, and extrapolation of the story (ie the adequacy of fortune-in-the-middle action resolution mechanics) rather than player narrative control.