You have a systrm or 2 or 3 you just… have down pat? That you have simply integrated into yourself at a core level, be it from reading over and over, playing, or running? That you could run checking the book only for some numbers and powder fine details? That you feel comfortable tweaking and customizing without worry?
These games in a way can form the framework of whole groups and campaigns, in a more folk practice format, the game existing more in practice than in a book. It’s a very special feeling to have a game internalized like this. It’s freeing, in a sense. And of course, as referee, your word is law, so in the classic but cliche “rulings over rules” fashion, the “game” as in rules becomes identical with the “game” as in play. It is custom fit, built for your table, kind of what the ill fated FKR ideally actually is.
For me I have 2 such games, Troika! and OD&D. I am going to be starting a local OD&D game, and I look forward to seeing how mich I actuay need to check the book, and if that changes over time. Just some thoughts ig, it’s late at night.
For me it’s three: Cairn, Maze Rats and some kind of OD&D (having “ruling over rules”ed it so many times I can switch the books under it without breaking a sweat).
Curiously, I never managed to memorize Troika!, I always end up having to relearn it from scratch.
Pretty much just Pendragon. I can very easily remember the task resolution of most games put in front of me, but when it gets to the ins and outs of combat and shit like that, the only one I can, with 100% confidence, run like a computer in my head is Pendragon.
And Pyrrhic Weaselry, but that’s like 2 or 3 lines at the end of the day.
Basic D&D is this system for me. I’m pretty used to handling the first 1-3 or 4 levels just from Memory for the most part. A Player might look up a Spell or something to get something specific, and I might need to know what a Pixie Saves As occasionally, but for the most part we’re pretty Invisible Rulebook with it initially.
More time with the system honestly. We played BECMI for a long time, and those decades of practice really helped internalize the rules for me.
I could probably manage 0e nowadays of course, but most of the Rulings and things I’d be filling in the blanks for would end up coming from some permutation of Basic anyway. Same with AD&D largely: Bolting on the Procedures from B/X or something just makes that game run smoother for me.