I had a few houserules that I've cut and pasted from my old campaign:
PLAYER CHARACTER STARTING OPTIONS
When making up a character, each is entitled to a special talent, skill, or family heirloom. To allow for this, a character may choose one of the following options:
a] One additional weapon proficiency slot.
b] A bonus of +5 to any non-weapon skill or four non-weapon proficiency slots.
c] Double starting funds.
d] A +1 non-magical item, including weapons, armor (up to and including chain mail), etc. One potion can be substituted for this non-magical item. This is a family heirloom or gift from the community, which should never be parted with casually.
DERIVED ATTRIBUTES
Perception is the character’s ability to notice ambushes, search for clues, smell or taste poison in foods, tell if someone is lying to him or her, and other actions that involve a character’s processing and analysis of incoming stimuli. A character’s Perception (PER) is determined by averaging their INT and WIS scores. A character with the Alertness Proficiency adds 1 to their PER when a proficiency check is made. Modifiers for PER checks range from +5 (obvious or fumbled ambush) to -15 (a successful Hide in Shadows/Move Silently check).
Non-weapon proficiency slots can be spent to raise PER by 1 pt/2 slots.
Willpower is the character’s ability to withstand torture, restrain oneself, and face powerful foes without flinching. Willpower (WILL) is equal to a character’s (WIS+CHA/2) + [level/3] (round fractions down). Modifiers range from +5 (staring down a weaker foe) to -15 (facing one’s death, fasting for 1 week). Failing a WILL test in a face-down situation incurs a -2 penalty to actions/initiative against the target of the check. Otherwise, a failed check usually means that the character gives in to their weakness. Non-weapon proficiency slots can be spent to raise WILL by 1 pt/2 slots.
Endurance is the character’s ability to exert his/herself for extended periods of time. A character’s Endurance (END) is equal to his or her (CON+STR/2) + [level/3] (round fractions down). The non-weapon proficiency adds 2 to a characters END score when a proficiency check is made. A character can become fatigued through three type of activities: Strenuous, Moderately Strenuous, and Mildly Strenuous.
Strenuous activities include running, fighting, and climbing. A character can perform such actions for a number of rounds equal to their END stat.
Moderately Strenuous activities include jogging, swimming, and rowing. A character can perform such actions for a number of turns equal to their END stat.
Mildly Strenuous activities, such as walking or riding, can be sustained for END hours)/ 2].
A character must make a CON (with a -5 penalty) check after this time. A failed check indicate that the character is Fatigued, incurring a -2 penalty to all Action Checks (see Modifiers below). Every 5 rounds/turns (or every 2 hours) past this check, whether it is passed or failed, requires another check at -5. This penalty accrues with each check. Failing a second check means that the character is Exhausted and must make a WILL check at -5 just to stay on his/her feet every round. Such a character can only defend (with a +5 AC penalty).
Recovering END
A fatigued must rest for an amount of time equal to the period of activity divided by 3. Characters with exceptional CON scores may subtract 1 round or turn (or 1/2 hour) for every 2 points above 14.
The minimum rest time is 1 round/turn (or 1/2 hour). A character that hasn’t slept at least 5 hours in a day gets a -2 penalty to their END check per (which accumulates from day to day).
WOUND STATUS
Wounds in AD&D are usually ignored (in terms of game effect) until the character reaches 0 Hit Points and passes out. In this game, wound status reflects the effects of wounds upon a character. As listed below under Modifiers to Action Checks and Derived Attributes, a moderately wounded character (one at 1/2 total Hit Points) receives a -2 penalty to all actions, including THACO, Movement Rate, ability checks, proficiency checks, etc. The Damage a character does is not effected, nor are Saving Throws or AC. When seriously wounded (the character has lost 3/4 of his Hit Points) this penalty becomes -5.
When a character is reduced to 0 Hit Points, he must make a CON or WILL check (with a -5 penalty for Wound Status) every round to remain conscious. In this state, the character may only crawl about, wrap their wounds, moan in pain, and defend themselves (with no DEX bonus). Every negative Hit Point adds to the -5 penalty to remain conscious. At -10.... you die!!!!
ACTION & ATTRIBUTE CHECK MODIFIERS
The following is a list of sample modifiers to character die rolls. Action Checks involve DEX, PER, STR, CON, END, movement rate, and all melee attacks.
Asleep: PER is halved, and 1 round must be spent waking (defense is possible with a +2 AC penalty).
Exhausted: -5 to all Action Checks.
Fatigued: -2 to Action Checks.
Meditating: PER is at 1/4 value and 2 rounds must be spent waking (defense is possible with a +2 AC penalty).
Reverie: PER at-5 in the first round. All action checks are at -3 and -1 (respectively) in the two rounds after reverie.
Wounded:
Seriously Wounded (1/2 total HPs): -2 to all Action Checks.
Critically Wounded (1/4 total HPs): -5 to all Action Checks. -2 to all other rolls (excluding Saving Throws).
COMBAT & WOUND NOTES
Critical Hits
On a natural roll of a 20 in combat, the character always hits. If a natural 20 is needed to hit, no critical hit occurs. Otherwise, a roll of a 20 on the d20 indicates that the character rolls twice the normal dice of damage and then adds modifiers for STR, specialization, magic, etc.... these bonuses are not doubled.
Fumbles
The opposite of a critical hit is a critical failure or fumble. In combat, a natural roll of a 1 on a d20 always misses. Furthermore, the character must make a DEX check to avoid injuring himself, another party member, or merely losing his weapon. A failed DEX check means that the character must roll another THACO roll. Another fumble here means the character hit himself for full damage. A 20 means that the character must roll an Item Saving Throw versus Crushing Blow for his weapon. Otherwise, the THACO determines whether the character hits the nearest friendly PC or NPC. A miss means the character loses his weapon and must spend 1 round retrieving it or drawing another one.
Called Shots
Sometimes, a character will try to hit a specific part of his opponent in combat. To perform a called shot, the character gets a -1 penalty to his initiative and a -2 THACO penalty (-4 for headshots or small areas such as hands, the neck, the groin...etc.) Possible effects of called shots include the ability to strike an unarmored portion of an opponent (thus improving the chance to hit, despite the called shot penalty), forcing your opponent to make a DEX check, forcing a CON check to avoid being stunned for one round (as per the old kick to the crotch trick), or causing double damage for a head shot or groin shot with a weapon.
Major Wounds
Another issue not covered by normal AD&D rules (perhaps rightfully so) is the area of disabling wounds, like broken legs, severed arms, etc. In this game, these types of wounds can occur in two ways (other than being hit by a Vorpal Sword or Sword of Sharpness).
The first way is by being brought to negative hit points. Any time a character is brought to negative hit points, at or below -7, he must make a Saving Throw versus Death Magic or permanently lose 1d3 points from 1d3 randomly rolled stats. This reflects irreversible tissue damage, scar tissue, and other not-so-fun things.
Furthermore, any hit from a weapon or spell that brings a character to negative 7 hit points or below; or does maximum damage on a critical, requires that character to Save vs Death Magic or lose the limb (or the permanent use thereof). If the character makes his Save, the limb is broken or injured and unusable for 3d6 weeks (minus a number of days equal to the character’s HP modifier from CON). A character with a severed limb loses 5 hit points per round as blood gushes from them (or...in the case of blunt force trauma...gushes internally).