I have decided to suggest a few modifications, based on my own experiences and the Russian guides I talked to. And to finish it all of, I compare my comments to the Known World mountain range altitudes listed in the Trail Maps supplement for Mystara.
If there's anyone out there with medical education / experience who reads this - or just climbing enthusiasts - please feel free to correct me on any of this :D
REGARDING ALTITUDE SICKNESS
The DMG simply states that people in areas with low oxygen, such as on high mountains, must make a Fortitude Save each hour DC 15 (+1 per previous check) and take 1d6 subdual damage each time they fail.
A character, who takes damage this way is automatically fatigued but can recover in normal ways when he returns to an area with enough oxygen.
Furthermore, characters above 20,000 feet risk altitude sickness and have to make another Fortitude Save DC 15 (+1 per previous check) every six hours and if they fail take 1 point of temporary damage to all ability scores.
My comments:
First of all, this does not reflect three (IMO) very important aspects:
1) Altitude sickness can begin as low as 3500 km or 11,500 feet.
2) It is possible to adjust your body to living at high altitudes with training and time.
3) The subdual-damage rule states that when your subdual damage reaches your exact hit points, you become staggered and if you take one more point of damage you fall unconscious. The rules should reflect that long before you become staggered you will be out of breath and unable to move (except very slowly), you will probably have headaches as well and feel very tempted to just sit down and rest.
I know that for a game system to fully reflect the many aspects of altitude sickness it would become unnecessarily complicated (dealing with such things as nose bleeds, dehydration and vomiting).
I propose a new system:
1) When a character reaches 11,500 feet must make a Fortitude save DC 13 or suffer Light Altitude Sickness. (described later)
2) For each 1000 feet he goes higher, the climber has to make another Fortitude Save and for each 1000 feet the DC increases by one. (e.g. DC 17 at 15,500 feet (approx. 4700 km)).
3) Each time the character fails a Fortitude Save, his condition increases one category from Light Altitude Sickness to Moderate Altitude Sickness to Severe Altitude Sickness. This condition lasts until the character reaches such lower altitude at which his condition was milder.
Example: Brennan misses a Fortitude save at 12,500 feet and suffers Light Altitude Sickness. At 14,500 feet he misses another save and suffers Moderate Altitude Sickness. If he goes down to between 12,500-13,500 feet he once again suffers only Light symptoms and if the goes below 12,500 he suffers no symptoms and begins healing again.
4) Each day a character spends at a given altitude without altitude sickness gives him a +1 bonus to the next Fortitude Save when he goes another 1000 feet up. This reflects that the body can slowly adjust to living at high altitudes.
LIGHT ALTITUDE SICKNESS
The character becomes fatigued and takes 1d4 subdual damage every 12 hours (no save).
MODERATE ALTITUDE SICKNESS
The character stays fatigued but movement is also reduced to 50%.
The character also suffers a -2 penalty on Intelligence and Wisdom because of headaches, nausea and other symptoms.
The character looses appetite and must make a Will Save DC 13 to eat or drink. If he does not, he begins to suffer from "Starvation and thirst" (DMG p. 86).
The character takes 2d4 subdual damage every 12 hours (no save).
SEVERE ALTITUDE SICKNESS
The character vomits continuously and cannot eat or drink. He suffers the consequenses of "Starvation and thirst" from DMG p. 86.
The character is exhausted (DMG p. 84)
The character also suffers a -2 penalty on Intelligence and Wisdom because of headaches, nausea and other symptoms.
The character takes 2d4 subdual damage every 12 hours (no save).
The character has to make a Will Save DC 15 every hour, to keep on moving, or just sit down where he stands.
Remember that being on a high mountain usually also means a "strong" or "severe" wind (DMG p. 87), cold dangers (DMG p. 86), the risk of avalanches (DMG p. 85), sunburns and snowblindness and the dangers of starvation and thirst if one does not eat and drink. Snow and/or ice hampers visibility and/or movement and fogs or whiteouts (zero visibility because of heavy snowfall) can lead to falling in a crevasse.
Suddenly, it becomes clear why a Ranger with a good Wilderness Lore skill can mean the difference between life and death to a party of adventurers!
If you like, you can introduce a new feat in your campaign: "Mountain Stamina" which renders a character immune to the effects of Altitude Sickness (but not cold, wind or starvation!!).
Now, looking at the height of the mountain ranges on the Known World from the Trail Maps supplements we see that 8 mountain ranges averages 11,500 feet or more: Colossus Mountains (Glantri), Glantrian Alps (Glantri), Icereach Range (Norwold), Kerothar Mountains (Alphatia), Kurish Massif (Sind), Makkres Range (Rockhome), Silver Sierras (Darokin) and the Wendarian Range (Glantri).
The Hardanger, Cruth, Altan Tepes and Broken Lands mountains are fairly low and pose no immediate danger of altitude sickness. (Although monsters and bad weather surely still is a danger!).
Comparing individual peaks we see that Odharjokull Mountain with its 15,750 feet in Soderfjord is roughly the equivalent of Mont Blanc in France and Mt. Elbrus that I climbed would equal Mt. Urapurda in Sind or Mt. Adruzzo in Darokin and require a Fortitude Save DC 20 to climb without problems (which I did not make, I don't mind telling you, *LOL*)
The DM should always try to keep track of the altitude of a group of player characters if they try to bypass a range of mountains without using known (low-altitude) passes.
Altitude should be an invisible danger in the mountains and one that merchants and other travelling parties would pay dearly to avoid.
As always, comments are very welcome!
:-) Jesper