V. III - pages 24-26. It's an attempt to deal with the problem many folks had with a human fighter (of whatever skill level) having more hitpoints than a giant.
I know in the 80s, many of the folks I gamed with had moved away from D&D - there were usually three main reasons: 1) lack of a formalized non-combat skill system; 2) the fact that armor reduced the chance of being hit rather than absorbing damage; and 3) hit points. None of them really bought in to the idea of hit points represent the ability to avoid actual damage.
The Arduin version looks like an interesting attempt to normalize hit points with actual physical bulk, while giving an advantage to people who make physical combat their specialty, and recognize that you do get (slightly) tougher as you go through and survive a rigorous life.
One of the things Hargrave seemed to stress was actually playing with rule-variants. I'd be curious to know how this one works in play.
OK, easy enough. How do characters gain hit points? Answer: Very slowly, as per below:
Clerics (and sub-classes): 1 hit point gained per every 2 levels Fighters (and sub-classes): 1 hit point gained per level Magic-Users (and sub-classes): 1 hit point gained per every 3 levels Thieves (and sub-classes): 1 hit point gained per level
For example, our cleric will have 34 hit points at 3rd level, 35 hp at 5th level, etc.
David Hargrave explains his reasoning behind this system thus:
'People now have a chance to run a character or characters on any expedition they choose without regard to difference in levels of experience. They can have their 1st level Warrior stand shoulder to shoulder with a 10th level lord and hold the gate together! Just as in real life young and inexperienced Warriors accompanied older, more experienced fighters. They fought and died together.
'Yet the higher levels have their own rewards, more (but not grossly so) hit points, better fighting ability and the like.
'Each now has a more secure place in game play because each can now play each and every game. No more will there be "high level" and "low level" expeditions. A player can recruit from all available characters, not just a few! No one is left out.
'And the danger of death is equalized for all, no matter how high level a character becomes.
'No more will there be characters practically unkillable because of their hundreds of hit points (in some cases fighters had triple the hit points of the Dragons they faced!!), who were virtually demi-gods! Those days are over if you use the new hit point system. Game test it. I'm sure you'll appreciate its fairness and playability. After all it was over 3 years in the making!'
(All the above information was taken from pages 24-26 of The Runes of Doom: The Arduin Grimoire, Vol. III by David Hargrave, 1978.)
A somewhat similar system (less complex, too) was also introduced in The Arcanum, which would become Talislanta.
It is a system that I have thought easy to use and cuts down on the complaining about rolling low. But, it also makes it impossible to roll high. For OD&D, I would actually suggest The Arcanum method, slightly modified:
Untrained classes (magic-users) get 2 HP / level Skilled classes (elf, cleric) get 3 HP / level Trained classed (dwarf, fighter) get 4 HP / level
To this, the character starts with HP equal to Constitution. A high Constitution might add a bonus, at the DM's ruling, to be added per level (to 9th.)
So, the two are very, very close to each other. One simply means the player's roll matters.
And there I stood, the giant at my feet. Mighty has the slain risen.