This is *RPG-ology #23: Nonrandom Thought*, for October 2019.

A long time back in *Faith and Gaming: Mechanics* we talked about Fortune, one of three methods of resolving outcomes in our games: the use of dice, cards, and other randomizers to create unpredictable random outcomes. We discussed then the question of how Christian faith relates to randomness.

Of course, the randomizers we use in our games are not entirely random. That’s what we’re talking about now.

As I was musing on probabilities, I read a headline that stated that there was a drive-by shooting in a nearby town. I’m sure that the town would like to think of itself as a city—it happens to have the largest geographical area of any municipality in the state, and I am told that police in our county seat jokingly refer to their law enforcement division as “the real police,” but it is largely rural space save for a long developed commercial district along three or four crossing roads. The headline surprised me, and got me wondering about the probabilities of being killed in a drive-by shooting. It appears that there are hundreds every year in the United States, so the probability of someone being killed in such a shooting on any given day is near one hundred percent—but the probability that it would be any specific individual is negligible, something that could not reasonably be anticipated.

Still, I doubt anyone would argue if I suggested that the probability of being killed in a drive-by shooting is significantly higher in sections of Chicago than it is in the rural counties of New Jersey. Such shootings may seem in one sense completely random, but they aren’t *completely* random.

That is our objective when we design fortune mechanics for our games: attempt to reflect the probabilities of any particular outcome. It is not particularly likely that a character would be killed in a drive-by shooting, but if we have that in our games we want it to be something that might happen in our cities and probably won’t happen in our towns. On our “wandering monster” tables, dragons are very rare and orcs rather common, because we envision our fantasy worlds as overrun by orcs but containing relatively few reclusive dragons. In some situations we achieve that by “curves”—the roll of three six-sided dice to generate character abilities in most versions of *Dungeons & Dragons* is a solid example. One character in two hundred sixteen will roll a natural 18 strength; a like number will roll a 3. One out of seventy-two will roll a 17, and a similar number a 4. Most characters will roll more or less ordinary strength, between 8 and 13, just as most people have average strength. The “randomness” is structured.

So, too, in combat, in most games there is a value that hits and a value that misses, and a range of values between the two for which how good the two combatants are, one at offense and the other at defense, determines which ones hit and which ones miss. There is randomness—you can always roll a miss no matter who you are—but it is controlled.

So how do you do that? This column can barely begin to scratch the surface of such discussions. The primer in *Appendix 3: Basic Dicing Curves* in *Multiverser: Referee’s Rules* is eleven pages long. There are a lot of ways to use dice to create different kinds of outcomes, and some of them are considerably more difficult to calculate than others. However, the calculation process is part of the game design process: you need to work out how your probabilities are falling. This will at least get you asking the right questions, and in today’s world once you’ve asked the question you can find the answer somewhere.

Probably.

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