and House Rules for My Home Game
I'm going to be running a Crystal Frontier game online, the first semi-public game I've run since the end of G+. In preparation rather then introduce my house rules piecemeal I've prepared a character generation and basic rules document for the game.
It includes the major subsystems for my house ruled version of Original Dungeons & Dragons (the 1974 pre-Greyhawk version, but not using Chainmail). This is the system I've used for several years and I find it works quite well for dungeon crawls. The goal is a quick, low complexity system that makes exploration a coequal element of play and can be used for online two to four hour sessions in an expedition based (each session you must leave the dungeon) campaign.
They make significant changes to the base OD&D system, though I think most of these changes fill in voids in the original rules or streamline areas where the design doesn't support contemporary games. At it's core though it should still be that same sort of D6 and D20 based flatter power curve, high lethality system as the original.