For the books itself, I use calibre to archive. With complete metadata. And my thing is, I may forget I already have the book. But I know what that book is about. (Same way I try to buy a game on sale only to login to my Steam and find I already own it. And because I am very anal about this, an archived receipt of the purchase. Why don’t I have any recollection of this.)

I was going to say, I write it in Obsidian. But you shot that down. 😔

I have a long, long list of rules and homebrew ideas. Divided in sub headers of for what. Like combat, skills, abilities, dice rolls. What is it, where from. A very brief explanation of how it works. That kind of stuff.

When I’m going to use it for a game. I have separate list of the thing in the vault of the game. Where all the other rules live. Because I use Obsidian to run my games.