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Old 05-29-2018, 04:06 PM   #1
Dalin
 
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Default Dice odds without dice

Situation: Road trip with the kids who ask if we can play DFRPG in the car. They remember their characters' key stats pretty well. I'm pretty good at making up scenarios on the fly. We have no dice and no digital tech.

What's the most elegant solution for determining success/failure without dice? I was thinking that if I knew the probabilities of success on three dice (e.g., from the table on the back cover of Adventurers), I could select a random number from 1 to 100. Then split the probability of success on both sides of the secret target and have the kids guess a number. So, for example, with skill 10, they have a 50% chance of success. If I picked 50 as the target, they would have to guess a number between 25 and 75 to succeed. If criticals mattered, I could say 49-50 is a critical success and 1 and 100 would be critical failures. Similarly, I could measure the degree of success or failure easily enough in percentage terms.

The scale would have to wrap around for this to work. So if I chose 90 as the secret target, with 50% odds, they would need to choose from 65-100 or 1-15 to succeed. 16-64 would be a failure, with 40/41 being a critical failure.

Does this make mathematical sense? Any wrinkles I'm missing? One concern was how could I pick target numbers "randomly." That's hard, obviously, but maybe I could use the tenths digit on the odometer combined, perhaps, with license plate numbers or passing signs to help me stay reasonably unpredictable.
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Old 05-29-2018, 04:20 PM   #2
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Default Re: Dice odds without dice

Buy a prize out of a gumball machine. Buy three dice that will fit inside of it, with one of the dice being an off-color. Instant 1d-2d-3d shaker.

Or, you can buy these at Walmart or Amazon.
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Old 05-29-2018, 05:58 PM   #3
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Default Re: Dice odds without dice

Steffan O'Sullivan (who wrote GURPS Swashbucklers, among other things) created the Sherpa RPG for (something like) this situation. He uses the last digit on a running stopwatch as a randomizer. An early version of the game is available online from the website linked.
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Old 05-29-2018, 11:01 PM   #4
Tom H.
 
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Default Re: Dice odds without dice

A possible option is to investigate the success mechanic in the RPG Cavemaster by Jeff Dee and Talzhemir Mrr.

http://unigames.us/shop/

I played this with the authors at a convention several years ago.

From what I remember, the player competes with the GM in which each separates and hides a number of skill stones between their hands. By randomly choosing the opponents' hands, a quantity of stones is revealed to determine a winner (and margin?) of the contest.

It may be possible to convert the mechanic to fit other random number generations.

Since it is supposed to be simple enough for our ancestors to play in a cave, it may be possible to adapt it to car travel. I guess it could be a bit hazardous for a driver to fiddle with sets of stones if he doesn't have an assistant . . . and may be hard to steer with fistfuls ;-)

Maybe you could somehow designate a number of "stones" in your virtual hands.
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Old 05-30-2018, 10:16 AM   #5
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Default Re: Dice odds without dice

Dice cups can also help, as well as using the lid of a game box (or other small box) to roll into. The box stops the die from escaping under a seat, and the dice cup helps everyone feel good about how random the roll is even though the box could be on a wonky angle.
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Old 05-30-2018, 12:11 PM   #6
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Default Re: Dice odds without dice

Smart phone or tablet with a dice roller app? Anyone?
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Old 05-30-2018, 12:14 PM   #7
Anthony
 
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Default Re: Dice odds without dice

Quote:
Originally Posted by evileeyore View Post
Smart phone or tablet with a dice roller app? Anyone?
According to OP: 'We have no dice and no digital tech.' Otherwise, yes, it's by far the easiest solution.
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Old 05-30-2018, 12:39 PM   #8
ericbsmith
 
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Default Re: Dice odds without dice

Actually, it just occurred to me you can get an Electronic Yahtzee game for under $10 that will serve as a dice roller just fine and last forever on a set of batteries.

While I realise that one of the stipulations of the original post was to not have dice, the problem is that you can't generate anything approaching truly random numbers without an external tool helping you (whether it's a deck of cards, dice, or electronic app/game). Humans are particularly bad at generating random numbers, so any attempt to do so without tools is likely to be skewed (purposefully or not). Even using license plates and road signs... which license plate you choose is a conscious choice, and they are not truly randomized as you tend to travel with similar vehicles on the road or see the same road signs multiple times.
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Old 05-30-2018, 01:25 PM   #9
Dalin
 
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Default Re: Dice odds without dice

Ultimately, it's clearly better to use a randomizing tool. (And thanks for the great suggestions along those lines.) We got to musing about the possibility of guessing numbers in the car, which then got me interested in the theory of how one could use guessing numbers as a randomizer.
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Old 05-30-2018, 01:39 PM   #10
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Default Re: Dice odds without dice

Quote:
Originally Posted by Dalin View Post
Ultimately, it's clearly better to use a randomizing tool. (And thanks for the great suggestions along those lines.) We got to musing about the possibility of guessing numbers in the car, which then got me interested in the theory of how one could use guessing numbers as a randomizer.
The problem is that humans are cruddy at randomization. Other than that, your method is statistically valid.
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