One of the biggest flaws of the Gygaxian combat system is that it is linear. An arrow does 1d6 points of damage. A Fifth level fighter has 50 hit points, give or take a few, how many arrows does it take to kill him in battle?
Answer is: ONE, if it hits. Anybody has any doubt that any medieval knight or a man at arms will not die, most likely, when an arrow tears his jugular, or hits him in the eye and goes in the brain? AD&D combat can be made non-linear and any arrow potentially deadly with an elegant critical hit system, that must deliver the fear of a SUDDEN DEATH! I combine the critical system mechanic from the second edition with the critical hit system from the Wizards of the Coast edition, for a very quick and elegant hope for every low lever adventurer. To put simply, ANY ATTACK HAS A CHANCE OF STRIKING A FIGHT-ENDING BLOW!!!!!!!! Note, that I didn't say, a killing blow. You can defeat any opponent in battle, ever the ones that can't be hit by non-magical weapons, but it does not mean that you kill them, only that they break off the fight. Why? DM can improvise and narrate: Vampire slips, falls down the stairs, turns into a wolf and runs away. The fire breathing demon sees something that it thinks will kill it, and flees to its primary plane of existence. To facilitate play, I do away with the traditional Hit location table. I have it, but it is optional.
Here is how the Midlands CritHit system works: Roll 1d20, 20 always hits, 1 always misses and you have a fumble (roll on critical fumble table - weapon breaks, you slip and fall, you drop weapon, etc.)
If you hit 5 higher than your To Hit number, you automatically inflict maximum damage!
If you roll 20 (for spears and axes), 19-20 (for swords), 18-20 (for curved swords), then your damage is multiplied (x3 for spears, x2 for swords, and x4 for scythes and military picks). Your regular To Hit Roll will tell you if you scored a critical hit and how much damage the opponent is in for. When you score a Crit Hit, you roll a second time to see if the opponent is out of the fight. If you score a second Crit Hit, then the opponent, no matter how big or invulnerable, is out of the fight!
If it is a +5 Crit Hit, the opponent is more scared than hurt, and breaks off the fight and runs or tries to surrender. If it is of the 19-20 Multiplier variety, then the opponent is more hurt and is actually incapacitated by the injury, and if the second roll is 20, the opponent is killed!!!!!!
Initially, I did not use a hit location table, and just improvised along, but then, to encourage the building of suits of composite armor by players and to aid in narration. Basically, if a player character wears a metal plate over a location that is hit, there is a good chance that a critical hit, and more importantly, the hit that knocks you out of the fight, will be averted. There are head, face, and neck locations, to account for metal skull caps, partial and fully enclosed great helms that the player characters might opt to wear. This also encourages the use of heavier shields.
I also have a detailed game mechanic (largely for the players benefits), to see of the crit hit knocks the player character off his feet, renders him incapacitated, knocks the PC unconscious, or puts them into traumatic shock. That one has great (and realistic) narrative results, but it needs me reviewing it, before I DM a game session.