James Edward Raggi IV (who really does have the coolest name in the OSR) posted a tentative solution to grappling/wrestling rules here and asked for feedback. Grappling rules have a history of sucking, but I like this subsystem a lot. It's straightforward enough I think I could recall it without reference, or recall something close enough to get similar results. However, one line caught my eye:
>>If there are multiple opponents attempting to wrestle a single defender, all attackers add their wrestling rolls together and then compare the total against the defender.>>
Just to clarify, all opponents add their wrestling rolls together, including the d20s, not just their bonuses? Let's say three PCs each with a bonus of +2 gang up against one monster. If they roll e.g. 18, 6, and 8 on the dice, you're looking at a result of 38. An opponent with a +18 bonus could tie on a natural 20. Even 2:1 odds are ridiculous: on average, a team of two can expect to roll 20 or 21 together, plus their bonuses. Only an exceptionally powerful *and* lucky opponent can have any hope to overcome such a duo.
It certainly makes sense that ganging up should be a significant advantage, but as the system is written, it pretty much outweighs the fighting ability of any participant. Is that the preferred effect? In my campaign at least, encounters are very often with groups larger than the party, composed of monsters or opponents who are individually weaker than the PCs. With this rule in place, the only sensible tactic is to dogpile the PCs until they are pinned. And when the party runs into one or two powerful monsters (that single horror arising from the mysterious well) their best tactic is to hurl themselves at it bodily. Even if it has tentacles and the associated bonus, a 1st-level magic-user with a strength of 7 has good odds of counteracting that bonus himself.
Here's my suggestion to preserve an advantage without making traditional combat tactics obsolete: If multiple opponents attempt to wrestle a single defender, the team rolls a single d20, adding melee Attack Bonus and Strength modifiers for all participants. [This already makes ganging up a decent tactic, but we can up the notch with the following add-on.] For each ally beyond the first, add a +4 bonus.
This "gang up" bonus still makes ganging up a significantly powerful tactic, but isn't as totally overwhelming as the original version. To go back to my first example, a group of three against one defender, where each of the three has a +2 bonus overall: if we assume the above roll of 18 was the group's roll, the result is 32 - a very strong opening. If the group's roll had been the 6 above, the end result would be 20 - able to overwhelm the common soldier, but that big tentacle-monster can probably cope. A gang of 2, assuming the same +2 bonus for each, would roll results ranging from 9 to 28, with an average of 18. A single opponent who is a bit more powerful than either individual has some chance, and even a weaker foe could get lucky. These averages are significant given that the system requires three wins to pin.
I expect that this method will allow the party to wrestle individuals into submission, but will preserve armed combat as the tactic of choice against groups and very nasty foes.