Rules and House Rules

Rules:
1st level starting PCs, AD&D 1e PHB only, stats are best 3 of 4d6, arrange as desired. Maximum hit points on first hit die. Starting gp is rolled for normally. Rolls are made in the chatroom.  If you don't like your rolls you can have 15 14 13 12 10 8 instead.
Death: At 0 hp to -2 hp a creature is unconscious but stable.  At -3 to -9 hp a creature is dying, losing 1 hp per round until death at -10 hp.
Raise Dead: There are legends of people being brought back to life, but this is viewed as a miracle that only legendary saints and the direction intervention of the Lord can accomplish.  Heathen priests claim to have reincarnated souls in animal form, and necromancers tied to the Dark Powers can reanimate corpses as shambling husks, or worse.
Magic Bonuses: Shield and armour AC bonuses stack.  Magic ring bonus counts as a magic armour bonus. For saving throws in most cases you use the best applicable magic save bonus (armour/shield/ring/cloak etc) only; a few powerful items like ioun stones provide a stackable bonus.
Replacement PCs: Upon the death or retirement of an existing PC, with the DM's agreement you may bring in a new PC with half the XP total of your old PC.

Equipment
Herdley Crossbow: This is a slightly improved light crossbow used by men-at-arms, brigands etc. FR 1 damage 1d4+1/1d4+1.
Arbalest: This is an improved heavy crossbow useful for sieges. It requires either a bipod stand or STR 16+ to fire effectively. FR 1/2 damage 2d4+1/2d4+1

Training: 
Training to Level Up takes 2 weeks, 1 week with a mentor at least 2 levels higher.  For an M-U to acquire a new spell of their choice upon levelling they need access to research facilities such as an arcane library, and then make the % chance-to-know roll.  If they fail to learn a desired spell they can repeat the study process with a different spell.  Each attempt takes 2 weeks, 1 week with mentor.

House rules:
Large shields give a +1 bonus to save vs dragon breath, fireball etc.  When not attacking or moving you can shelter behind a large shield, treating it as cover in addition to the regular bonus (large shield 50% +4 AC, small shield 25% +2 AC).
Race: 
Humans (only) get young adult and mature adult age mods, ie +1 STR +1 CON if age 21-40. This is to make them viable vs demi-humans.
Class: 
Thief ability % chances may be modified by up to +/- 50%, as with magic resistance the base numbers are used for a roughly 11th level challenge or threat, +/- 5% per level difference. 
Assassins can be Neutral or Evil. Assassination by weapon usually requires a to-hit roll before the % assassination chance can be rolled.

Distance - Range inches (") in individual combat are treated as 10', both indoors and outdoors.  For mass battles, range inches outdoors are treated as 30', 10 yards.
 
Movement
When moving cautiously and mapping, a group always moves 120' in 1 10-minute Turn.


Race       Base Move  Medium Armour   Heavy Armour
Human/Elf etc  120' (40')        90' (30')        60' (20')
Dwarf              90'  (30')        60' (20')        60' (20')
Gnome, Halfling  90'  (30')        60' (20')       45'  (15') 
You can always adjust position up to about 10' in a combat round if not actually restrained.  


Combat Movement 
I'm combining the AD&D rules with BX, where you can move 1/3 your base move then attack.
Full Move: You move - 'run' - your full base move, no attack. This includes running away; enemies get a free attack at your retreating back.
Charge: Full Base Move then Attack at +2 to hit, either lose DEX bonus or -1 AC penalty if no DEX bonus.
Move & Attack: 1/3 Base Move (as per brackets above), then attack normally.
Fighting Withdrawal: You can attack then back up 10'.


Movement with Missile Fire
Fire Rates assume load & fire, no movement (but you can always adjust position up to about 10' if not actually restrained).
FR 1/2 or 1: If you start with weapon ready/loaded you can fire once, then do a 1/2 move.
FR 2: You can fire once and 1/2 move. 
FR 3: You can fire once and 2/3 move, fire twice and 1/3 move, or even fire once, 1/3 move, then fire again!


Multiple Melee Attacks - Fighters (including subclasses) do not get 1 attack/level vs 0th levellers. For Fighters with 3/2 or 2/round attacks, or two weapon fighters, all attacks take place on your own initiative. You can move up to 10' during your melee attack routine. If you move (1/3 full move rate), or charge (full move rate) you cannot move again during your attacks.

Moldvay B/X style unified attribute modifiers: eg STR 16 would give +2 to hit & damage instead of 0/+1. I  keep the % Reaction table though since it's worked so well in play.
The full attribute table is as follows:
2: -4
3: -3
4-5: -2
6-8: -1
9-12: +0
13-15: +1
16-17: +2
18: +3
19: +4
(Girdle of Giant Strength):
19: +4/+4 dmg
20: +4/+5 dmg
21: +4/+6 dmg
22: +4/+7 dmg
23: +5/+8 dmg
24: +6/+9 dmg
DEX mod applies to reaction/attack/AC, WIS mod to save bonus, etc.

Weapon damage modifier by STR
1-handed weapons add normal STR bonus to damage, as do missile weapons designed specifically for a high-STR wielder.
2-handed heavy melee weapons (Two-handed Sword, Bardiche et al) add +2 damage per point of STR bonus.
Off-hand weapons used for a second attack (dagger, hand axe) add  +0.5 damage per point of STR bonus, rounded down.
Thrown weapons - normally +1 dmg per point of STR bonus, except light throwing weapons, those with a fire rate greater than 1, eg daggers & darts; due to their lightness & high fire rate they do +0.5/point of STR bonus. If you attack with a 1-hand main weapon and also throw dagger or hand axe from off hand, which I allow, the off-hand missile is +0.5/point of STR bonus.


Shield Training
PCs who can use shields can take a Weapon Proficiency slot in shield use.  This gives the following benefits when using a large shield:


1) Can two-weapon-fight (-2/-4, DEX mod applies) with shield as off-hand weapon, it does 1d3+STR bonus damage, and can push a S or M foe 5'.  PC loses shield AC bonus until his next attack.


2) You gain the following base AC shield bonus, instead of the normal +1:


Unarmoured: +3 (AC 7)
Light & Medium armour - Leather through Chain: +2
Heavy armour (Splint, Banded, Plate): +1


Thus:
Plate + shield: AC 2
chain or band/splint + shield: AC 3
Scale & shield: AC 4
studded or ring + shield: AC 5
Leather & shield: AC 6
No armour + shield: AC 7


Striking to Subdue
Attacks to Subdue are between 0 and -4 to hit, depending on the weapon used and any helmet or armour worn by the target - club vs unarmoured target is -0, trying to sudue a plate-armoured target with the flat of a longsword is -4.  Most subdual damage is temporary damage, recovered at 1 hp/hour, however 1/4 of subdual damage (rounded down) is treated as real damage.


Unarmed Combat
With Proficiency (unarmed) a character may attack for 1d2/1 + STR bonus.
Otherwise non-proficiency penalty applies, and damage is always subdual damage.

Combat Rounds
I don't use segments, rounds are variable in duration and generally not a minute long - as a guideline they're typically between 10 and 60 seconds depending on the size of the battle.