starting hit points: Constitution score + special Constitution bonus + race base + class base
Note that Arduin has many more races and classes than your typical D&D game. In the interests of my fingers, I will give the scores only for those races and classes found in D&D.
Race Base
Dwarves, female: 18
Dwarves, male: 19
Elves, female: 20
Elves, male: 21
Gnomes: 16
Half-Elves, female: 15
Half-Elves, male: 16
Half-Orcs: 13
Hobbitts, female: 11
Hobbitts, male: 12
Humans, female: 15
Humans, male: 14
Class Base
Fighters (including sub-classes): 5
Clerics (including sub-classes): 3
Elven Fighter/Magic-Users: 3
All Other Classes: 0
Special Constitution Bonus
13 Constitution: 1
14 Constitution: 2
15 Constitution: 3
16 Constitution: 4
17 Constitution: 5
18 Constitution: 6
For example, say you have a 1st-level male human cleric with a 14 constitution. He would start out with 33 hit points, as the following break-down reveals:
14 (Con score) + 2 (Con bonus) + 14 (race base) + 3 (class base) = 33
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.)