Reserves

The D&D convention of inflating hit dice has always stuck in my craw.  That is:  hit point totals which increase in proportion to creature level.

As a representation of bodily health it seems absurd that a character who could be killed at first level would be able to take a direct, full damage hit from a two-handed sword, or fall off a cliff, or even a direct hit by a missile (in some sci-fi offshoots), and survive unscathed.

Over the years it's been put forward repeatedly, apparently even by the game's author, that hit points are not a measure of the character's physical integrity alone.  They instead represent a nebulous sort of luck, internal energy and survivability.

But while I can understand this idea, and it would make some sense in certain games, it still doesn't sit well for two reasons:

1. Although the immunity caused by hit points builds over levels, the damage done by a typical melee attack increases very little, especially in early editions of the game.  This means that while the hit points are measuring some abstracted plot protection, the weapons are still doing concrete, discrete ranges of damage.  This kind of damage dealing is the sort of thing my mind associates with "realistic" portrayal.
2. Hit points may do well at representing narrative immunity in some respects, but in several editions of the game "insta-kill" type phenomena still exist.  These are things that will kill you dead without regard for your large number of hit points.  Where's your protective cloak of luck, circumstance, and internal reserves then?

Over the years I've considered several alternatives to this state of affairs, flip-flopping between "realism" and plot protection:

• Alternatives that remove inflating hit points almost completely, like Ken Hood's Grim n Gritty system(s).
• Alternatives that abstract the separate the luck/energy reserves aspect of hit points and sequester it separately from the "bodily damage" aspect, as with Vitality and Wound points.

But neither quite fit.  The removal of inflation entirely speeds up combat and arguably makes combat more realistically deadly, but it makes characters incredibly fragile against higher level threats.  Vitality and Wound points restore the character's durability, but Vitality still has no influence on survival in other areas of the game.

For the Crude Simulation Engine I'm considering a different solution to the issue:  applying a resource pool similar to hit points and using it not only for to allow survivability against damage, but also as a "fuel"trying to increased survivability in other areas, power magical abilities, and allow heroic actions in other areas.  The idea is to allow greater flexibility of use while keeping management aspect of a long-term dungeon crawl always at the forefront.

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Hit Points & Reserves

Hit Points
Characters have a maximum number of hit points equal to their Constitution score.  Normally the only way to increase your maximum hit points is to improve your Constitution score or grow significantly larger.  Creatures larger or smaller than medium size multiply their Constitution* by a modifier to determine hit points**:

Size	Modifier	Height or Length***	Weight***
Fine	1/12	6 in. or less	1/8 lb. or less
Diminutive	1/8	6 in. - 1 ft.	1/8 lb. - 2 lb.
Tiny	¼	1 ft. - 3 ft.	2 lb. - 8 lb.
Small	½	3 ft. - 4½ ft.	8 lb. - 60 lb.
Medium	1	4½ ft. - 8ft.	60 lb. - 500 lb.
Large	2	8 ft. - 16 ft.	500 lb. - 2 tons
Huge	4	16 ft. - 32 ft.	2 tons - 16 tons
Gargantuan	8	32 ft. - 64 ft.	16 tons - 125 tons
Colossal	12	64 ft. or more	125 tons or more

* - Incorporeal undead typically are treated as having a Constitution score equal to their Wisdom for this calculation.  Corporeal undead substitute 2x the number of hit points per inch according to Table: Substance Hardness and Hit Points.
** - Round down.  Minimum 1 hit point.
*** - Height, length and weight are just approximate values to better estimate a creature's size.

When a character's hit points are reduced to zero by damage, the character is incapacitated and dying (loses a point per round).  At -10 hit points the character is dead.  Characters who are stabilized through first aid recover 5% of their hit points per day of rest or 10% if they receive standard medical treatment.

Magical healing - Magical healing and similar techniques always restore lost hit points.  Magical healing never restores lost reserves.


Reserves
In addition characters from adventuring classes, and most monsters, have additional points to represent mental, physical, and supernatural reserves.  A character's pool of reserve points accumulates at a rate based on character level:
Warrior:  5 points of reserves per warrior level
Mage:  2 points of reserves per mage level
(Monsters generally follow the warrior progression unless otherwise noted.)

Reserve points can be spent as follows:

• 1 point per point of damage avoided.
• 3 points per 1d6 bonus to a saving throw, attack roll, skill check and damage rolls.  This excludes rolls made as part of a magical spell or similar effect.
• Each spell cast costs a number of reserve points as follows:

Spell cost = (Spell level x2) -1

(zero level spells have no cost)

Reserve points may be spent at any time a roll would otherwise be made, even after the roll is made, as long as the character has enough reserves remaining to spend.  The character may spend multiples of 3 points to add multiple d6 dice to any roll if they deem it necessary.  Of course in doing so they're limiting their own ability to survive attacks later on.

Reserve points spent during a day refresh after a good night's sleep.  If a character has had extremely bad sleep, or suffers other problematic conditions (i.e. dehydration, starvation, sickness, etc.), they may only be able to accumulate half their maximum reserves.  In some extreme cases they may not be able to accumulate reserves at all.

Feat:  Spell-like Ability / Wild Talent

A character taking this feat may choose a single spell or similar power (e.g. psionic discipline) with a level equal half their character level (rounded down).  Even if the character is not a mage they may use their own pool of reserves to activate the spell as if they were a mage of a level equal to their character level.