So I've been thinking, during various random day dream opportunities, about how tricks (to use the Savage Worlds terminology) could work in Labyrinth Lord or other old-school D&D type games. For non-Savages, the SW tricks system basically allows one character to gain a combat advantage over another by means other than a standard attack. They're divided into Smarts and Agility tricks - the former being anything that tries to confuse or get one over on the opponent, and the latter being anything that tries to unbalance or hinder the opponent. It's a super simple system, and one which can be used to resolve a huge variety of spur of the moment combat maneuvers.
So to convert it over to D&D, there needs to be two components:
1. A system for resolving whether the trick succeeds.
2. A definition of what hapens when a trick does succeed.
The latter is easier. At first I was thinking about Armour Class penalties or stunned conditions, which would be fairly close, mechanically, to the effects of a trick in Savage Worlds. However, a reading of the AD&D description of what Hit Points represent put me onto a different track - the 1e rules explicitly state that HPs are abstract, and include all sorts of factors like fatigue, luck, combat expertise, etc. So, with that in mind, actual normal damage seems like a pretty good effect for a successful trick (albeit fairly low damage - 1d3 perhaps). Probably with the caveat that a trick cannot kill - it can't reduce a character to less than 1hp.
Resolution of a trick's success is more troublesome, and I've not managed to come up with a satisfactory solution yet. The most obvious candidate would be an opposed Int or Dex roll. But in old-school D&D books, how many monsters have an Int or Dex score? None. The AD&D monster manuals give an Int rating, which could easily be converted to a score, but it's still an extra step to do that conversion. But as for Dex, there's no simple way to work it out.
Ability checks also of course have the problem that characters can never get better at them, unlike saving throws or THAC0, which improve with experience level. It'd be nice for certain classes to be able to get better at certain types of tricks - any kind of Mountebank or Bard type class, in particular, would suit this kind of advancement.
Another possibility I considered is that could tricks be resolved with a simple attack roll? That solution would certainly be simple, but an attack vs Armour Class just doesn't make sense for an agility type trick (where heavy amour would usually be an impediment rather than an aid to resisting the trick), and is completely meaningless for a mental type trick.
The search for a solution continues...