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Thursday, April 11, 2019

Last-Minute GM: Random List Picks

I’ve been messing around for some time trying to come up with a good basic procedure for picking something at random from an arbitrary unordered list. Prepared tables with numbers indicating dice results are easy, but it would be nice to be able to grab just about any list and pick something randomly. But I hadn’t found a method that was satisfying until now.

You need two dice, usually a d4 and a d10 numbered 0 to 9. The d10 is how many lines to skip, while the d4 tells you where to start and what to do with the d10.
  1. Start at top of list and skip down 0 to 9 lines.
  2. Start at the top and skip down 10 to 19 lines (d10 + 10.)
  3. Start at the bottom and skip up 10 to 19 lines (d10 + 10.)
  4. Start at the bottom and skip up 0 to 9 lines.
This lets you pick from a list of 40 items. If you only have 20 items, don’t add 10 to the d10 for results 2 and 3. Some other dice can be used instead of the d10, if you have a different number of items:
  • d4 + d6 (reading 6 as zero): 24 items
  • d4 + d8 (reading 8 as zero): 32 items
  • d4 + d12 (reading 12 as zero): 48 items
  • d4 + d20 (reading 20 as zero): 80 items
Always read the highest number on the second die as a zero, so that one of the results will be “use first/last item on list”. For the middle results of the d4 (2 and 3,) add the number of sides the die has to the result.

You can also use a d6 instead of a d4, with this chart:
  1. Start at top of list and skip down 0 to 9 lines.
  2. Start at the top and skip down 10 to 19 lines (d10 + 10.)
  3. Start at the top and skip down 20 to 29 lines (d10 + 20.)
  4. Start at the bottom and skip up 20 to 29 lines (d10 + 20.)
  5. Start at the bottom and skip up 10 to 19 lines (d10 + 10.)
  6. Start at the bottom and skip up 0 to 9 lines.
This gives you a range of 1 to 60 items.

There are other tricks you could do for two-column lists.

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3 comments:

  1. For a list of 40 items wouldn't it be easier to roll 1d4 and 1d10 and derive the line from two?

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    1. It's technically the same either way, but in practice, I think it's easier if the number you count is low, in other words, 20 or less. This is why I split the d4 roll and count from 1 to 20 from the top or from the bottom.

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    2. I do have another idea, though, which might be even easier. I'll have to do a follow-up post tomorrow.

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