Original Edition Delta is my set of modifications (house rules) to the OD&D game, with selected additions from the Greyhawk supplement. These include: (a) replacing Clerics with Thieves, (b) simplified weapon damage and effects, (c) lightweight "stone" encumbrance system, (d) clarification of the combat sequence, and (e) other mechanical streamlining (which I call the "Target 20" system).

Click on the image to the left to download the brief PDF file. Remember to print as "Booklet/Brochure" to match the format of the original little books. Also available in OpenDocument Text format, with added designer notes in sidebars, here. For ongoing discussion, visit my D&D blog, here. Some more details on the "Target 20" system in particular are here.