As in any grand campaign, the occasional side trek during world building can make for a nice change of pace. I expect this post to be the first of many.
One of the fun parts of tampering with the fundamentals of a system you're intimately familiar with is that all the little stripped gears that never quite worked for you are rattling around in the back of your mind while you fiddle with other pieces that you expect to survive the edit largely unscathed. The attributes are one of those safe bits. I humored the optional "subabilities" from the Player's Option: Skills & Powers book for all of three minutes (I'd never given them more than a cursory skim before), and considered stripping out exceptional strength or altering this or that table to even out the benefits a bit, but ultimately, I mostly decided against. In most cases, I felt torn. I happen to like the attributes as they are, with their scarce bonuses at either extreme--but a lot of players have been trained by the last few editions to see bonuses as necessary to a worthwhile character instead of being, well... bonuses. The deciding factor in the cons column ended up being that I'm going to have a lot of hexes to fill, and already likely to end up with a good sized stack of changes that I'll need to run every stat block through.
So it looked like the attributes were going to escape the knife, short of clipping a little fat from the edges of the tables. Then I came to the Constitution chart.
Immediately, we lop off the Poison Save and Regeneration columns. The rules may stay, but they needn't be included on the chart or default character sheet. Second, my players have grown accustomed to a degree of generosity on HP. Knowing that I intend to be much more strict on that front generally, I decided to throw them a bone by moving that first asterisk from 17 down to 14. So far, pretty minor.
Now, I generally give Gygax the benefit of the doubt about his having reasons for some pretty strange design decisions, but System Shock and Resurrection Survival being separate yet virtually identical always confounded me. (If anyone can answer for the choice, I'd love to hear an explanation!) So we'll go ahead and remove Resurrection Survival. It's an arbitrary choice which one goes, but System Shock as a name seems appropriate for both. It's also one of those things I never did much with, and I wanted to give it a chance to be something cool.
As it happens, two PCs had died in my 3.5 Forgotten Realms game the previous week, and the party only had the resources to raise one of them. She was sorely disappointed about the level loss, and I have to say, with full cognizance of the threat this admission represents to my OSR cred... I kinda-sorta-maybe-a-little-bit agreed with her. Level loss has always been a book keeping nightmare when taken literally, and even when treated as just a -1 to hit and -5 max hp, it does have a tendency to escalate. I made the decision pretty early on that I wanted to strip level loss from my rules entirely, in favor of Constitution loss. I wasn't entirely happy with that either, to be honest. It made a sort of sense, but it still felt wrong. Not so much for Forgotten Realms, or standard fare "assumed setting" D&D for any edition, where being raised from the dead is a trivial matter beyond a certain threshold of wealth, but definitely for the game I'm looking to build and the setting I'm looking to present.
A resurrection is a miracle. It isn't a spell that a cleric prepares--it's an act of the gods, bestowed upon individuals deemed by heaven to possess a fate as yet unrealized. There's nothing in the world wrong with games where that isn't the case, but it is going to be the case in this one. That being the case, I can't conceive of a reasonable justification for why the gods would only perform most of a miracle. A character worthy of being plucked from the immutable and inviolable throat of the grave must surely also be worth whatever a point of Constitution costs such a god to bestow. Of course, a point of Constitution in 2nd Edition with Method I characters is hardly a replacement for a lost level. Chances are good that you've got a 0 hp modifier already, and could have your life drained three or four times before you felt any appreciable impact from the effect.
Timidly, you reach for the dust-covered sheet that drapes limp over a flat, vertical shape. The sorcerer's rumored scrying mirror, you think. You tear off the sheet and look upon your reflected visage. Suddenly it screams; a hideous, deafening shriek that freezes your joints and grits your teeth until they feel as though they might splinter in your mouth. You can't look away from your own face, eyes gone to milk and flesh twisting into the creases of age in mere seconds. Finally, you tear free of the sorcery, hunched and groaning, and raise bone-thin fingers to touch your ancient face. You lament your stolen life, and know that... uh... you can't, um, run as far without resting anymore. Uh... plus you can't hold your breath as long. *Twilight Zone Theme*
It's not ideal, is my point. So with all of this floating around in my thoughts, I'm passively typing the relevant bits from the chart into my Constitution table. 65. 70. 75. 80. 85... hey, wait a second. This is a pretty good stand in for maximum age!
From there, the idea more-or-less constructed itself over the course of a few minutes. System Shock is malleable. The Constitution chart provides the base starting value. At character creation, you subtract your starting age from your System Shock score. Each year, knock off another point. When struck with life-draining magic, it takes a non-trivial portion of your life expectancy away (as well as hope of surviving a future traumatic injury). Potions of longevity and fountains of youth add to it, along with perhaps some new spells. It's nice because the closer you come to death by natural causes, the less able you are to withstand the kinds of things that provoke System Shock checks. But that shouldn't go one way--if anything, physical trauma should reduce life expectancy. Tack on 1d10 damage to your System Shock total each time you trigger a check.
Now to trigger some checks, and it couldn't hurt to balance it out with a little kindness. Considering what I said earlier about removing resurrection except in the most special circumstances, how about if a character reduced to 0 hp gets to make a System Shock check to cling to life? That seems like a good trade. And besides, a hard rule about death by natural causes serves our design principle #4: Time Passes Meaningfully.
As non-human PCs will be scarce in my world, the problem of longer and shorter-lived races is a non-issue, but if you want to implement something like this at your table then making System Shock proportionate to maximum age rather than directly isomorphic should be a trivial matter.
Here is the rule as it appears in my Player's Guide:
System Shock: This is a character's percentile chance of surviving magical effects that reshape or age his body, such as petrification, polymorph, magical aging, etc. It may also be used to retain consciousness in some situations. Additionally, this number determines the percentile chance of a resurrection attempt being successful. When a character is reduced to 0 HP, a System Shock check may be rolled to determine that they have fallen unconscious instead of dying. In the case of humans, this number is lowered by 1 each year (other races modify this change proportionate to life expectancy). Any time a System Shock check is successful, this number is reduced by 1d10, reflecting the effect of grievous wounds on life expectancy and future recovery. System Shock may be considered an estimate of the number of years a character has left to live if her conditions do not change. If the System Shock value reaches 0, the character dies.
Not bad for a stroke of inspiration, and we're still on Chapter 1!