The goal of Demon Idol is to catalog AD&D rules and rulings for easy reference, interpreting them in a gamist fashion.
Gamism is a style of adventure gaming focused on game mechanics that minimize DM fiat, provide meaningful decisions, and create an emergent story. In gamism, the world develops as a consequence of the game, rather than the game being a tool to “tell a story”. This is in contrast to “rulings before rules” style where the DM throws away rules or fudges/skips die rolls to create a result that “makes sense” to them. It is also in contrast to “storygaming”, where the game system comes second to the story that the DM wants to tell (i.e. “railroading”).
In gamism, rulings are for when the rules are silent. Gamists also favor rules interpretations which create a clear, understandable system that the players can rely on without needing to wonder how the DM will rule. Put simply, it tries to run the game like a game!
There is a lot of non-gamist and storygaming advice online about running RPGs. But there are many people who prefer gamism, so we made this site for them.
When we started our campaign, we knew that we wanted to play BTB. For us, that means respecting the game by following the game rules closely in order to gain practical understanding of those rules and provide a framework players can rely on. We've played quite a lot now and we've changed very little – we've found that AD&D works pretty well as written.
However, D&D is a “DIY” game – it's meant to be a living game which grows with your group's campaign and evolves over time into something that is special to your individual campaign. This includes the way that you interpret the AD&D rules and the rulings you make, but it also includes ways that you extend the rules to best suit your table. This works best when you first understand the system you're building on, which is why trying to play BTB is a noble pursuit.
When you go to play AD&D BTB, you'll find that you need to look up a lot of things. Some of them are “gotchas” like "why do the books say two separate things about how much magic armor weighs?", but most of them are situations where rules create interactions that aren't covered by the books. A lot of questions will be raised even if you've read the books cover-to-cover. To find the answers, neophyte AD&Ders must turn to old magazines like Polyhedron and Dragon, and read posts on forums like Dragonsfoot and Knights & Knaves Alehouse. As we went through that process, we wrote down everything we learned. Demon Idol is the result.
As your campaign evolves, you may have the same questions we did. When that happens, you can use Demon Idol as one reference for making the rulings that best suit your campaign. Over time, you'll end up with your own set of rulings that make your campaign unique. That's DIY D&D.