Here’s how to run Apocalypse World, Dungeon World, etc. with d20s instead of 2d6.
This is just for fun. Not claiming it’s “better” than 2d6. Just for anyone interested to try it to capture the rolling a d20 vibe.
For a straight up d20 roll with no modifiers, use this:
1-8: Failure (mark XP)
9-16: Partial success
17-20: Best outcome
Then adjust bonuses like so:
Score: Modifier
1-3: -6
4-5: -4
6-8: -2
9-12: 0
13-15: +2
16-17: +4
18: +6
In general, you can just double a modifier, like when you move +1 forward, just move +2 forward instead.
Doubling modifiers like this makes it a bit less accurate than the 2d6 model, but much easier to use and remember. The trade off should still work fine.
This approach is remarkably similar to rolling a 2d6. Not down to the penny or anything, but totally workable if you want to try a d20 roll for fun.
I don’t remember the ability bonuses (one of the things I wish they wouldn’t have kept from D&D, but I get why it’s there).
Are you basically doubling the bonuses?
Also, just curious, have you run numbers on percentage of outcomes? D20 is linear, while 2D6 averages between 6 and 8.
For the record, I like rolling D20’s. I’m genuinely interested.
Yes, I’ve run the math, and then afterward figured out it works remarkably well to double the modifiers in this case.
So, what this does is basically mimic the curve with very similar percentages. There’s some minor fudging on percentages, but it’s “close enough” to match the curve.
The 2d6 mechanic is deceptively simple. While it does indeed run along a curve (which shifts with modifiers), having only 3 possible results is really just three batches of outcomes that are easily quantifiable as percentages. So, with a little rounding, and some minor cheating at the edges of the curve, the d20 matches pretty well!
How did you compensate for the probability bell curve?
Ryan M. Danks DW ability bonuses are kept from D&D. Basic D&D.
Adrian Thoen, the probability curve is a distraction. What’s important is the probability to get above or below certain numbers.
Miss
2d6 is 6 or less: 41.67% chance
1d20 is 8 or less: 40% chance
Partial Success
2d6 is 7 or more: 58.33% chance
1d20 is 9 or more: 60% chance
Full Success
2d6 is 10 or more: 16.67% chance
1d20 is 17 or more: 20% chance
With Matt’s percentages, you can do the same with a 1d10 or 1d5, which might be better for playing with young kids. Unsurprisingly, a 1d30 works even better replicating 2d6.
Oliver’s got it exactly!
Thanks for this. I’ve done the same thing for my D&D 4e game just to get a little more DW in there, but I was never sure on the numbers.
Thanks much! I must confess that while I am not regretting most things about migrating my games to DW, one of the biggest things I miss about D&D is rolling a d20.