Almost any attack may be declared as Subdual - the attacker is assumed to be using the flat or pommel of a weapon, or simply pulling blows and aiming at non-vital areas.
When damage is caused by a Subdual attack, half is assumed to be 'real' damage, which heals at the normal rate, and half is non-lethal damage, which heals much more quickly. See Healing for details. For the purposes of knocking someone out, the full amount of damage dealt counts, however.
When a Subdued victim does fall unconscious, they will not bleed and lose further HP. However, any further damage inflicted, by any means, is always lethal.
Less Than 1 HP
More colour and options here; these rules make falling below 1 HP a bit less fatal, especially for people with high Con scores. They also allow the player with a badly injured character to still take part, even if only to mutter a stirring Final Speech:
Any creature with less than 1 HP will usually pass out. But it's possible to stay conscious by rolling under Con on 2d10, with a penalty to Con of their current HP. While below 1 HP, a creature who remains conscious can crawl or drag themselves along, bandage themselves (via healing), speak haltingly or perform other minor actions. Any action that requires a Non-Weapon Proficiency roll (e.g. healing) will also be at a penalty of their current HP.
If their HP are negative (not just 0), each further round they will lose another 1 HP, and have to make a further roll to stay conscious. Any character whose HP total has reached a negative value equal to their Con dies.
Firing Missiles Into Melee
Because all those involved in a melee are assumed to be actively parrying, dodging and maneuvering, it's dangerous for others to try to hit a target in the melee with a missile weapon. This system tries to take into account the size and numbers of the potential targets and the attacker's own skill.
First determine the sizes of all the creatures involved in the melee, on all sides, except for the intended target. Add the sizes together - Tiny creatures count as 1, Small 2, Medium 4, Large 8, Huge 16, and Gigantic 32. Compare this total with the size value for the intended target as a ratio. The attacker must then equal or beat the number given on the table below (using 2d10) in order to target as intended. If he fails, roll randomly between all the other combatants to see who's being shot at.
A shot at the wrong target is assumed to attack at THACO 22.
Note that any Fumble while Firing Into Melee automatically targets an ally; there's no need to calculate or roll.
Ratio of Size of Target to Size of Others in melee
5:1 or better
4:1
3:1
2:1
1:1
1:2
1:3
1:4
1:5 or worse
Right target
3
5
8
11
14
17
20
Wrong target
The attacker gains a bonus to this targeting roll, equal to: Missiles bonus for Dex + Specialisation bonus
Additional Weapons
Here's a selection of weapons from Pangea, my long-running campaign. A few of them are specific to certain cultures, and bear out my belief that Dwarves are hard-done by in AD&D. The Goblin Bow may seem overpowered here; below I give increased damage values for other bows.
NB: Missile damage for other bows: Shortbow - 1d8, Longbow - 1d10, Light Crossbow - 2d4, Heavy Crossbow - 2d8
Polearms
The traditional band of dungeon-goers rarely equip themselves with polearms more unorthodox than a spear. This is despite AD&D's exhaustive list of exotically-named long weapons with peculiar spikes, blades and curlicues on the end. I assume EGG's wargaming background leaked through there... Anyway, these rules exist to give PCs and their hirelings more reasons to try polearms out, along with new and appropriate tactical options.
For the purposes of these rules, the polearms category includes any hafted, two-handed weapon over 6' or so long. For example, the 2H spear listed above, as well as the usual pike, halberd and glaive-guisarme. The standard spear isn't included.
Polearms work best if there's a set of them in use together and pointing in the same direction - they're great for aiming down dungeon corridors or for use in battlefield formations, trusting in both cases that your allies won't let the enemy come in from your flanks.
All polearms can be braced against charge; this allows first strike on a charging foe (unless they've got weapons even longer), which inflicts double damage.
Polearms can be used from the second rank of a formation. They can either parry on behalf of someone in the first rank (giving the bonuses to AC described here), or they can be used to harass and distract a foe, which gives allies in the first rank +1 To Hit them. A maximum of two second-rank polearms can be used to help each front-rank fighter.
A polearm that's facing in the wrong direction for fighting (e.g. a foe has approached from the flank or rear) gives a 5 count Initiative penalty to the wielder's attacks.
This system attempts to account for such things as lassoes, nets, bolas, which are not intended to cause immediate harm to the target.
The roll to hit with an entangling weapon ignores armour, but not Dex bonus, ready shields or the like.
Nets
On a hit assume that the net, if large enough, has entangled the victim. Entangled victims cannot use long weapons or cast spells with Somatic components. If the attacker still has hold of the net, in subsequent rounds the attacker may roll an opposed Str vs. Str roll to pull the defender off his feet.
Entangled victims can cut their way out, if they're caught while holding a slashing weapon or have natural weapons like claws - assign the net a nominal number of HP and allow the victim automatic hits against it every round. Alternatively, a successful Bend Bars/Lift Gates roll can be used to burst the net via main force.
Lassoes, bolas and similar
Roll for the effects of any successful hit:
2d10:
Effect:
2-4
Caught round target's throat; takes 1d4 non-lethal damage each round unless throat is armoured*
5-10
Caught round target's arms and chest; arms immobile until rope cut or successful Bend Bars roll made*
11-13
Caught round target's waist; no added effects*
14-20
Caught round target's legs; legs immobile and will fall unless rolls 1d20 under Dex-4*
* In all cases, the attacker may make an opposed Str vs. Str roll to pull the defender off his feet, each round until the rope is cut.