We have a few considerations to apply to this, however: the first being that the whole mountain is not evident to the players, when the decision must be made. For a full measure of the mountain, the whole mountain would have to be viewed, and from good, clear vantage points, trusting the weather holds. It can take a couple of days to march around a good-sized mountain ~ assuming it can be marched around, as it might be part of a range, which might make the far side of the mountain very difficult to assess. Secondly, the mountain needs to be assessed by someone who knows how; an experienced mountain climber can "see" more in the falls and curves of the landscape that most of us can. It wouldn't do any good to send the flying mage on a tour around the mountain, unless the mountaineer (more likely a ranger) can go along.
Now add to this that parts of the mountain can't be seen at all from the ground, making themselves evident only once the players are actually in the act of climbing. A good looking route can have a surprise along the way, where a cleft only 12 feet wide ~ virtually invisible from most places on the ground ~ suddenly makes the route impassable. The same can be said for overhangs and surfaces that turn out to be less than solid. Ice and snow are additional variables that are largely impossible to predict.
The only real surety about choosing a route comes from having climbed the mountain before ~ either personally or in the form of a guide. Nearly all the difficult mountains that were climbed in a rush of ardor with the rise of 18th & 19th century Romanticism were attempted before a climb was successful, often many times. Like a ship exploring a coastline in the new world, mountain climbers would attempt different routes and make copious notes or drawings, seeking the measure of the task before surrendering, returning to the valley.
It became evident that there were summer routes and winter routes; routes that risked fog; routes that were dangerous due to crosswinds that would create sheets of ice or made balance difficult (changeable winds that could be deadly for a flying mage trying to land on a rocky and uncertain ledge); routes of all kinds.
Still, we want a rule set that encapsulates at least some of this. I don't think any of it can be limited to a set formula of time vs. space. Rather, I see a series of "wagers" that the players face. They can, initially, choose the slower path, which might get them closer to the goal before having to take serious risks, but nothing with a dangerous mountain can be certain.
So the first task is to determine how dangerous is this particular mountain? Right off, I find myself seeking an established system of some kind. Growing up near the mountains, I'm familiar with a rating system that's used for ski trails: a green circle for easy slopes, a blue square for intermediate slopes, a black diamond for advanced slopes and a double black diamond for expert only slopes. In Europe, the system is different, with pistes described as green, blue, red and black, with double or triple black diamonds, orange (extremely difficult) or yellow (ungroomed and unpatrolled).
Obviously, much of a mountain can't be skied at all, but I see no reason not to employ the spirit of the system. Rather than trying to specify a whole mountain as "difficult" or "easy", individual routes along the same mountain can be described as a string: green, green, blue, green, black, blue, green, black, black. We can then produce simplified versions of "piste maps," such as the one shown below:
|Click HERE for full size|
We don't have to get anywhere near this complicated. With a little imagination, we can apply a string of "dangers" to, say, Wildstrubel in the upper left hand corner, with those evident cliffs, uncertain snow fields and glaciers. We can then see how forks in the string would allow a choice to go left or right, because this way looks "blue" rather than "black" ... even though it might end in a triple-black diamond climb another hundred meters above, where we can't see.
This leaves us with a meaningful resolution for the wagers the players would try: I would suggest that, in terms of success, we see the scale as a series of descriptions, that could be employed by the DM to the player, without actually describing the actual roll that would be needed for success (we do want the wager to have an uncertain quality, though the rule must be rigorously adhered to by the DM ~ no fudging!). Slopes can be "safe," "easy," "chancy," "tense," "tricky," "risky," "hazardous," "improbable" and "impossible." This gives us two wagers for each of four types (North American system) or eight wagers among eight types (European system).
In each case, we inform the players ahead of time that the way ahead "looks tricky" suggesting that there is a very reasonable probability that they won't succeed ~ perhaps guaranteeing failure unless someone with experience attempts it. I should think "tricky" would be the most dangerous an amateur should probably attempt - anything above that is bound to mean a serious fall or accident.
Now, this is the sort of thinking that I'm encouraging where it comes to making rules for anything. Start by describing how the players might solve the problem (assessing the mountain before climbing); then, defining the structure of the problem (dangers mountains possess, nature of mountain routes). If possible, use established ideas from professionals dealing with those problems in the real world. Then, figure out a way to map it (pattern string based on danger code) and then to communicate that map to the players in a way that enables them to make multiple decisions over the course of the adventure.
Then, having established this framework, we can go ahead and add other details, events, monsters, problems and obstacles, in keeping with the motivation-adventure path I described last month.
What's missing from the above are the multiple results that might arise out of failure - and success too, which might increase the character's ability to climb and assess other mountains, as well as perhaps an experience adjustment for characters making mistakes and taking damage. I'm going to forego this, as I'm starting to get involved in another project. I don't know if I'll come back to this making a rule series ~ right now, I don't see much else to say about it. I am open to questions, however, and as readers know, questions tend to inspire me to go deeper into subjects (the adventure path link was the result of a reader's question, nyet?).