I was flipping through my copy of the 1e DMG today and realized that it's the only place I've ever seen a discussion of probability in a game book. (This may be because I haven't been reading the right RPGs.) This is how Gygax decided to open his Dungeon Master's Guide, and it makes a lot of sense: a thorough discussion of the tools of the trade. But as with a lot of what I've noticed about the DMG, there's a very specific attitude embedded here, and one that's really different from the one I associate with the later editions of the game that I got into the hobby with.

What I find interesting here is that Gygax assumes that you're going to be building your own random tables, or using the dice to adjudicate results on-the-fly. You've got to know how your dice work, so you can get them to give you the randomization or oracular input you need. Instead of a series of universal mechanics that, in theory, cover everything, you get some basic principles that help you make the decisions you need to make as they come up.

What opening the DMG with a discussion on probability says to me is: Sooner or later, you're going to need the dice to help you resolve something that the rules don't cover, or to give you some ideas to handle some wacky thing that your players just did. Which is just about exactly what I want the beginning of a guide to running a game to say.

That's a good insight. It's those pages that first taught me about probability.

ReplyDeleteAnd I know some people get tired of the theorizing about play instead of just playing, but this concept of knowing your tools is what drives me to understand what underlies dungeon/creature/item design.

Speaking of probability, is there a web-app out there that calculates probabilities based on the number and types of dice?

ReplyDeleteLooking at the original chainmail rules, they have a plethora of combat tables, that use numbers of dice and target numbers. I was thinking of turning those into percentages, but I don't want to "do the long-hand" math on the probabilities

Note also that, in AD&D, Gary often seems to me more interested in the raw chance of success and lists a specific die roll almost as an aside.

ReplyDeleteTravellerBook Zero didn’t discuss probability, but it did include probability tables for 1d6, 2d6, 3d6, etc. (Travellerwas d6 only.)I call it the “unified unsystem”:

1. Think about all the factors involved.

2. Determine the % chance of success.

3. Pick a die roll that matches that chance.

@Paladin: This one seems pretty nice; let's you pick target numbers and graphs results:

ReplyDeletehttp://ojaste.ca/dice.html

In looking for that I stumbled across this pdf that might be of everyone's interest:

http://www.darkshire.net/jhkim/rpg/systemdesign/torben_rpg_dice.pdf

Oddysey, you are right on target. :D

ReplyDeleteThanks for the link.

ReplyDeleteI crunched the numbers for the old Chainmail combat tables, and discovered that I need to buy horses for all my characters.

Gary was an insurance buy at one point, wasn't he? Probabilities, frequencies, intensities, those are like candy for insurance guys.

"What opening the DMG with a discussion on probability says to me is: Sooner or later, you're going to need the dice to help you resolve something that the rules don't cover, or to give you some ideas to handle some wacky thing that your players just did. Which is just about exactly what I want the beginning of a guide to running a game to say." Excellent insight. It's exactly the right thing right up front, the DMG really does a tremendous job of that sort of thing. My old dog-eared copy is falling to pieces and is upstairs in storage right now, but I'm going to go dig it out now. Incredible stuff in that book. Very likely the single best thing Gygax wrote, utility-wise, at least. IMHO, of course.

ReplyDeleteJohn Wick did a bait-and-switch/homage to EGG's probability discussion in one of his L5R books.

ReplyDeleteBasically the introduction and first two pages were a big, fat, willfully opaque, polysyllabic lie about the importance of having accurately modeled simulationist trade systems in your home game. There was even a bell curve table in there IIRC. Turn the page and the narrative voice basically says:

"Right, timewasters and nosy parkers discouraged; here's the real skinny..." and switches to what the book is /really/ about.

wv: shiden - the mysterious dice cult of Rokugan.