Thanks to a post on theRPGsite, I’ve just discovered the Searchers of the Unknown RPG. A one page set of rules for playing old-style (aka early TSR) D&D modules. Here’s the concept from the rules pdf:
A typical old-school D&D module stats list for a monster looks like this: (AC6, MV9’, HD 1, hp 4, #AT1, D1-10 by halberd). The idea is that, if it’s enough for monsters, it should be enough for PCs too. This light-rule system enables to play these modules in that way.
The game looks like it would work fine provided everyone already knew the basics of “playing D&D.” You can find a downloadable copy of the rules here.