I was futzing around with age tables, writing out some established rules for placement on the wiki, when I ran into an old rule in the Dungeon Masters Guide (DMG) that I hadn't considered for a long time: Death Due to Age.
I remember the rule of course, but it's obscure because except for one combat with a ghost a party of mine had decades ago, I haven't aged anyone with magic ... and no character has played enough years in my campaign to come close to death from old age. I played one group for ten years and the total time that passed in the game was only six years. My offline campaign ran for nearly nine years and they only moved a little more than three years in game time. Die of old age? Hah.
Player characters are considered above the norm as people (they roll 4d6 instead of 3d6), so we make a simple exemption (as did AD&D) to dying of natural causes before the age of 61, with the exception of disease of course. There are no worries about it until then.
Now, my game does not recognize the extended lifespans of demi-human races; it did not work for my history or my conception of game play, so I ditched it about 30 years ago. AD&D does give different calculations for the non-human races' starting character age in the DMG ~ when I made the change over, I used those starting ages and converted them to human age. It turns out dwarven and gnomish clerics start very late in life; in human terms, the gnome cleric starts at 48 +1d10, while the dwarf cleric starts at 57 +2d4. The average age for a starting dwarf cleric is 62. Something to keep in mind.
Okay, the table. Once a character reaches 61, the first progressive roll at the top of the chart is applied (and then scratched out by the character). The character rolls 5d12, indicating the number of months that will pass before the character makes a fate check ... or if the reader prefers, an Atropos check. This is a percentage roll, calculated first by the character adding his or her present constitution to 80. John, with a 14 constitution, would calculate a 94% chance of survival.
Now, we can narrow this down to the day of the check, if the DM has it together and is keeping good records. John's birthday is March 11th and he turns 61 in the year 1651. He doesn't roll that well with 5d12, getting a 28. This means he won't need to make a fate check until at least July 11th, 1653. We can simply roll a d30, not worrying about the quibbling issue of the length of months, getting a result of 14. On July 25th, 1653, John will make a fate check, to see if he was fated to die that day.
That's a long way off and John doesn't worry. Look at how many years you can play a D&D campaign with 28 months of game time! But the day approaches, and approaches ... and even though he knows the day he will have to roll, he doesn't actually know if he's going to die that day. Let's say, he has a feeling.
But the day comes and John is fine. He rolls a 53 and all is right in the world. Now, he rolls the second row on the chart: 5d10. He rolls and gets slightly below average: 25. Again we calculate, of course from July 25th. John will make his next fate check (rolling a d30 = 10) ... July + 25 months = same date in August, two years later, add the 10 ... September 4th, 1655.
Once the character is down to 1d4, thereafter a fate roll is made every 1 to 4 months, +1-30 days. A lucky fellow might linger on.
But of course, there's always a longevity potion. I think to really make this system work, I'd attach a system shock survival roll to the longevity potion ~ and for those who are familiar with AD&D, the roll to survive system shock is generally worse than the roll I'm giving to dying of fate. That makes it a tougher decision ~ which I always like as a DM, because I am a major prick.
Seriously, though, I never expect to use this table. A character aged by a ghost should have to make each check that is passed through by the aging process. That's only fair.
What would death be, exactly? Well, probably just that the character dies in their sleep. Or rolls, fails, and collapses suddenly of a fatal heart attack. Or a brain embolism. Hell, I'd let the player pick. It isn't that important.
But there you are. A tension-building rule that could haunt a player through a year-long campaign, and seriously cause them to question whether or not they should just "hang out in this town for a few months while the mage researches something."
Maybe that's wishful thinking on my part.