Introduction

This website contains two bodies of work that are designed to be read together.

The first is the Advanced Dungeons & Dragons 1st Edition Dungeon Master’s Guide Overlay (DMGO) — a section-by-section record of the relationship between the Advanced Dungeons & Dragons 1st Edition Dungeon Master’s Guide (DMG) (Gary Gygax, TSR, Inc., 1979, ISBN 0-935693-02-4) and the Oath-Bound rules system. The DMGO does not reproduce the DMG. It mirrors its structure and records the decisions — what was kept, what was changed, what was discarded, and what was replaced with something built specifically for Oath-Bound.

The second is the Oath-Bound Rules Module (CRM) — the live rules themselves. Where the DMGO records the relationship to the DMG, the CRM expresses what the Oath-Bound rules actually are. Cross-references throughout the DMGO point into the CRM; the two are meant to be used side by side.

You need a copy of the DMG to use the DMGO. It is not a standalone rulebook. The CRM is standalone — it can be read independently — but its decisions make more sense when the DMG context is visible.

The DMG’s internal organization is, to put it charitably, idiosyncratic. Sections, subsections, and nested entries do not follow a consistent hierarchy, and the relationships between topics are not always where a reader might expect to find them. It would be possible to rationalise this — to extract a clean hierarchical tree and impose a more navigable structure on the material.

That was considered and rejected.

The DMG is a product of its time — the early output of a new and emergent design discipline that had not yet settled on conventions for how rules documents should be organised. That idiosyncrasy is baked in, and it is at this point simply what it is. The problem is most visible at the page layout level: major sections and even chapters can be easy to miss, their headings not always distinguished from the surrounding text in ways a modern reader would expect. Readers who know the book have already learned to navigate this; readers who do not will need to find their way around it regardless of what the DMGO does.

Rationalising the structure here would help neither group, and would introduce a second organizational scheme to reconcile against the first. There is also a legal consideration: the DMG is a copyrighted work, and mirroring its structure as a reference framework — without reproducing its content — is the approach that keeps the DMGO redistributable. A rationalised derivative structure does not obviously improve that position.

Where page references are provided in the DMGO, they are there for exactly this reason — to offer at minimum a coarse navigation aid against a document that does not always make its own landmarks obvious.

The structure of the DMGO is therefore the DMG’s structure, quirks and all.

Oath-Bound uses percentile dice (d100) as its primary resolution mechanism. This was a deliberate decision made in the early 1980s, consistent with what many Game Masters (GMs) were doing at the time, and its consequences are felt throughout the system — in combat, skill resolution, and the treatment of minor magic items.

The conversion is not total. d100 was adopted where granularity adds value. Where a d20 provides adequate resolution, it was left alone. The appendix random generators are the most visible example of this — they remain unconverted because converting them would add complexity without adding anything useful.

A GM who prefers d20 resolution is not excluded from using Oath-Bound. The world design, the fictional framework, the theological and economic models — none of these depend on percentile dice. The d100 elements can be replaced with d20 equivalents with minor accommodations at most game tables. The rest of the system travels intact.

Parts of this website and substantial parts of the broader Oath-Bound corpus were produced with the assistance of AI tools — principally Claude (Anthropic) and ChatGPT (OpenAI). That is worth being honest about, both because the contribution was real and because the nature of it is probably not what you might assume.

The design decisions are not AI’s. The world, the rules, the opinions embedded in the DMGO — those came from decades of play and the particular convictions that accumulate over that kind of time. AI did not design Oath-Bound. What it did was something more useful than I expected.

The first thing it gave me was discipline. Game design, like most creative work, tends toward productive tangents — interesting questions that lead somewhere worthwhile but not where you were going. Left to my own devices, those diversions accumulate. Having an agent that tracked the thread of an argument, pushed back when a decision was underspecified, and kept the session aimed at a defined outcome turned out to matter more than I anticipated. It is not that the diversions were wrong. It is that they needed to be logged and returned to, rather than allowed to swallow the original task.

The second thing was organization. The raw output of a design session — the decisions, the rationale, the edge cases — is not a document. Turning it into one requires a kind of editorial work that is slow and unrewarding to do alone. AI was consistently useful at taking a body of confirmed decisions and producing structured, navigable prose from them. The thinking and much of the language is mine. The shape of it on the page often is not.

Beyond the rules work, AI was also used extensively in world design — and here the role was different again. Building a coherent world requires a kind of relentless internal consistency checking that is easy to defer and hard to do alone. Having an interlocutor that would push back on implausible claims — "that mountain pass is in the middle of a seven-day march through wilderness, which has consequences for trade routes, garrison logistics, and the plausibility of that town being there at all" — turned out to be one of the more valuable parts of the process. The world gets more internally consistent when someone is paying attention to the gaps. AI was willing to pay that attention at two in the morning when no one else was.

Every page on this website carries a :content-origin: attribute in its header — Human, Claude, ChatGPT, or Mixed — that records where the content came from. That record is immutable. It does not change as pages are polished or revised. Readers who want to know the provenance of a specific page can find it there.

The Advanced Dungeons & Dragons 1st Edition Dungeon Master’s Guide — the DMG — was written by Gary Gygax and published by TSR, Inc. in 1979. All rules content in that document is the property of its respective rights holders. Nothing in the DMGO reproduces that content. Section headings are used as structural references only, in the same way that a commentary cites the work it discusses.

Original hardback copies of the DMG, and its companion the Players Handbook (PHB), have become collector’s items. First printings command significant premiums and clean copies at any printing are increasingly hard to find at a reasonable price. For practical working use, Wizards of the Coast has made both books available as PDFs and print-on-demand editions through DMs Guild:

The Monster Manual (MM) is not directly addressed in the Oath-Bound ruleset at present, but it is strongly recommended. With one caveat — its treatment of creatures defined by alignment as Good or Evil does not translate directly into Oath-Bound, where that ontological category does not exist — it is a near drop-in compendium of enemies and livestock to populate your game. The creatures are there. The Good and Evil labels are not a property of the monsters themselves in Oath-Bound; they are a product of their relationship to the pantheon and to the people encountering them. That reframing requires almost no mechanical work, and their inclinations and responses towards adventurers should be relatively easy to referee.

The print-on-demand editions of the PHB and DMG reproduce the 2012 premium reprints rather than the original 1979 printings. The content is identical for the purposes of the DMGO. Page numbers and chapter bookmarks are consistent with the originals — references cited throughout this website can be trusted against either edition.

Which brings us to an utterly shameless plug.

If you and your players can work from reprints or electronic formats, getting started costs very little. This website has free access. The DMG and PHB are available as modestly priced print-on-demand editions. Two books plus this website will carry you a long way — and that is the GM’s burden, not the table’s.

Players will find the PHB useful, but in a system where rules awareness is expected to emerge through play, and character generation is a process undertaken with the group, it is not mandatory. A player who wants to read ahead can, just as one who would rather just sit down and play is not disadvantaged.