D66 Overlap Tables

 

 

The D66 table made it possible for games that only use six-sided dice to stay true to themselves when they needed a random pick list. The first incidence was almost certainly Traveller, but I associate it most strongly with Troika these days.

Briefly, roll a d6 for the ones place, another for the tens place, and consult a table of 36 options. This is more than enough for most random tables, and you can reduce the options by lumping results together (i.e. 1,1 - 1,2) and expand upon it by adding dice (D666, etc.) or nesting results. See this page for some common variants.

Birth of D66 Overlap

Anyway, I like them quite a bit. I was just writing one up for post-apocalyptic weather in ROACH (working title), when I got an idea. I was thinking of using the entire D66 table for fall and spring, rolling twice and taking the highest for summer, and the lowest for winter. It struck me how awkward it is to roll a D66 twice, and how it was a bit of a stretch to still get hot weather in winter and vice-versa, even if it was less likely. That's two counts against it.

So what if instead I made the D66 table partially exclusive - fall and spring would still read the D66 and span the entire table normally, but summer would read the highest die first, and winter would read the lowest first - reducing their possibilities. Except for doubles, this would split the table during summer and winter. This may be a bit weird to wrap your head around until you see it in action:

• Doubles (11, 22, 33, 44, 55, 66): put all the results possible during winter and summer here. In this case I put all the gonzo apocalyptic weather here, as it did not feel overly seasonal.
  
• Lows (12-16, 23-26, 34-36, 45-46, 56): put all the cold or wintery results here, plus a few of the warmer ones because the climate is a bit too warm, even winters can run a bit hot.
  
• Highs (21, 31-32, 41-43, 51-54, 61-65): put all the hot or summery results here.
  

I like to split these up as above when designing the table, with three columns for the 6 common results, 15 lows, and 15 highs. I even made a spreadsheet that automatically sorts them into a regular D66 table format to keep things convenient. You can find it here if you want a template for your own uses.

For example, the weather table I was referring to above:

This was made by entering the list into a spreadsheet - the column on the left with entries stacked together for the low (blue), high (orange), and both (clear) lists is on the left. To the right, it restacks the types into a D66 list in regular order, you can see how it shuffles them for publication style.

(coloring added due to a good suggestion by "PolarFrosty" on the OSR discord)

I'm not too concerned with whether I was the first one to think of this. RPGs suffer from a lot of lost history. It is useful to me however, and I am damn well using it. If this sparks any ideas for any of you, feel free to comment below.