This thread got me thinking about pacing in games and mechanics for keeping track of the passage of time.

http://www.odd74.proboards.com/index.cgi?board=general&action=display&thread=4783&page=1

I'm interested in simple, abstract game mechanics for keeping track of how much torchlight or how much breathable air the player characters have. Can anybody recommend me a game (other than D&D) that has such a thing?

umm... usually breath holding is based on the character's endurance.  Like 1 minute per point or something like that.  After that the attribute itself starts to take damage.  when that depletes the character usually dies or becomes unconscious.

If the character takes attribute damage but survives, then the attribute damage should heal naturally and quickly, like one point every 15 minutes or something like that.

For amount of air in a combines space, I would figure what people use per minute of air then determine the general amount of cubic feet of air in the space. 

I am a diver so I know that 100 CF of air will last me about 2.5 hours at the surface with low activity.  This is called SAC: surface air consumption.  My SAC is about .6 which means I use about .6 CF of air per minute at moderate levels of activity and/ or stress.

So in a 10' x 10' x 10' room there is 1000 CF of air.  At my SAC it would take me about 3333 minutes to use it all, more if i was resting or even more if sleeping.  That's about 55 hours.  Just divide that number by the people in the room to determine how long the air will last for.  Also this is SCUBA where anything you breathe is completely lost during exhale.  You might need to do some research to determine how much percentage of oxygen is retained and what is converted to co2.

There is another problem.  As the people exhale more and more c02 is released and therefore the mix of air is becoming toxic.  This means even if there is plenty of 02 to breathe the c02 could start to poison the people.  I'm not sure at what that point it happens.

hope this helps :)

Quite frequently, I've seen games essentially sweep concerns like that under the rug.  Essentially, what you're looking to do is escalate conflicts and situations.  The best advice I have on that is, if it'd be interesting that the torches went out, and it's been a decent chunk of time, poof, they're out.  If it'd be interesting that a room is short on air and the characters have about half an hour of time before they start to asphyxiate, then go for it.  Gotta say, though, if what you're looking for is a timer to compel the players to keep moving, honestly, torchlight or air in a dungeon are pretty drab ones.

Consider a dungeon that represents, oh say, the lair of a dragon.  Eventually someone's got to notice these armed and armored buffoons clanking around the upper levels, and they'll report back to the dragon, who will entrench his defenses; now the later encounters are tougher, the enemies have cast all their buff spells and put on their heavy armor, summoned reinforcements...  Don't treat the world outside the PCs as a black box; if they need pressure to keep moving, all you have to do is figure out what adversity might happen naturally and press.

Apocalypse World has an abstract mechanic called the countdown clock. It's a clock face that looks like a pie chart with divisions at 3, 6, 9, 10, 11, and 12. The rules suggest using it for anything where timing is important. As stuff happens, you mark off a pie slice. Stuff doesn't really start to get serious for PCs until you reach the 9:00 stage.

Why not using real time?

People often claim about D&D that everybody figure out problems engaging a combat. Combats take time, a lot of time. So, if you put a clock over the table and give a couple of hours, players are going to think how to avoid combats to finish before running out of light or air.

With those countdown clocks, the important takehome is that the countdowns generally don't advance unless the players essentially don't take initiative.  When it's "time for something to happen", that's when you advance the clock.  In general, unless there's a "plotline" reason for the clock to advance, it doesn't until the PCs neglect the situation at hand, preferably in favor of some other potential problem, but possibly due to inattention or indifference.

I'm cool with time limits, don't get me wrong.  It's just that air and such, I think, are boring.  Say the princess is going to get slain as a hostage in four hours, and make that the time limit.

Watch out using one-to-one time, though.  Sometimes it can take twenty minutes to describe ten seconds in character, and sometimes the other way around.  The idea is to guard against player characters screwing around, not to punish them for necessary attention to detail.