I saw this “advantage” system in another game (don’t remember which) so I tried applying it to PbtA games. Basically, instead of adding +1 to the result, you roll an extra die and take the best two. Likewise for +2 you add two dice, take the best. For -1, you add a die, but take the worst two. ANYWAY I wanted to see how the odds matched up to the classic method, and the results are in. Close enough for hand grenades.
In short, if you’d rather roll 5 dice and pick two instead of roll two add three, it’s give or take in the same ballpark. There’s technically diminishing returns, you’re on a curve instead of a line, but the scope of the results is so narrow that you really don’t feel the difference.
Anyways. Point is, PbtA isn’t broke, not fixing it, this is just a flavor change. Also, nevermind the Crit column, I wanted to see if it affected rolling boxcars at all.
P.S. – I also tried adding advantages and disadvantages (so, roll 4 dice, remove the best and worst) and it was statistically insignificant from just cancelling them out. So don’t bother with that.
https://docs.google.com/spreadsheets/d/1E_uqZ3W9D9h2VB2XhllyYZ9iZkO_9SK76vzTZLFypQk/edit#gid=0
The Advantage/Disadvantage thing AFAIK was originally from D&D5e (where it was by far the most interesting and original thing in it), but has been adopted by a few other games, though the only PbtA game I know of that uses it is Fellowship.
Actually the advantage disadvantage die system was in the Call of Cthulhu 7e playtest at least as early as 5e development.
I think Advantage/Disadvantage shines most when you combine it with normal +Stat stuff.
As in replace +1 forward, with +die forward?
Ewen Cluney I know the advantage/disadvantage mechanic is included in a number of in-development PbtA games, mine included, so I imagine it will be seen a lot more in the next year or so.
From strictly a numbers standpoint, from my chart what I gathered is that A/D gives you a greater variance on a single bonus (one die is more potent than +1) but then evens out to be the same at +2 and +3…ish. So it’s good if you want +1/-1 to really feel like a deviance from no modifier, A/D shifts the scales a bit more out of the gate.
But for me? I’m an old WoD player, so I have a fondness for throwing handfuls of dice.
Lemmo Pew it’s be neat to see how a “roll the pool and count successes” mechanic could work with PbtA sensibilities.
Aaron Griffin I won’t lie, I might have ended up here because I was trying to do that at one point. But I started this hack like, 2 years ago and it’s changed shape so many times…
Aaron Griffin Also, you get points, the whole reason I revisited this graph is because of your comment on that Turtle World doc. I had the stats for A/D vs. +/- worked out already, but I didn’t know if adding A’s and D’s was different from cancelling them out. Glad to have that solved.
It’s also used in Mongoose Traveller 2, and first showed up in D&D with the 3.5 edition book about the Nine Swords.
I love the historical lineage tracing that’s going on.
For more of the lineage, you can sail on back through history to Mechwarrior 2nd Edition for the earliest appearance of this mechanic that I have seen with its change to Natural Aptitude~
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I feel like Warhammer (the war game) has used this kind of thing for many years.
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This is relevant to me.
I mean, it’s not that “roll more dice take the best” is some revolutionary idea, it’s more that the math shows that on the scope of most PbtA games, it’s similar enough to adding bonuses to the sum that you can get away with it. I think it’s interesting that in the scope I outlined, the fall-off is also in the same range. What I mean by “not viable” is that the odds are so skewed, that you shouldn’t consider rolling in those conditions from a narrative perspective. If you’ve got three disadvantages, you’re best looking at what those are, and really decide if you have a snowball’s chance in hell.
I should say that A/D has a slight benefit in that it’s never mathematically impossible to be shifted out of a success/fail bracket, since you’re always taking the sum of two dice, your result will always be between 2 and 12. It’s just not statistically relevant on the edge cases. But if you have a gambler in your playgroup, they may just want to take those odds. I dunno.
I’m not a stats guy – how does a single A/D+Stat roll compare to +1 forward?
Aaron Griffin To answer your question first, you’ll notice in the +1 graph, all the numbers just shift up a value with +1. So you can look at the A/D graph, and just shift the numbers as well.
However, in the game I’m constructing, stats ARE the A/D mechanic. If you’ve got 2 in a stat, you add two dice to the roll. So I don’t mix methods, though I can see the appeal for doing so since a single advantage is more than you get from a +1. I just believe that whatever you do, adding complexity to the table slows down the game. I’m not saying addition is hard, but if I’m doing the A/D method, I want to roll however many dice I need, then look at the results on the table and grab the two best dice. Fast, easy, and always the same. I’m that dummy at the D&D table who always forgets that some bonus is in effect, or that a certain condition applies. I try to mitigate stuff like that in my own designs. Or rather, apply all the conditions before dice get involved, so that the roll is the roll and you are ready to move the narrative forward after.
I’ve playtested Adrian Thoen’s Impulse Drive, and it uses A/D to great effect. But it’s not additive– you never get even more dice on a “+2,” that just doesn’t exist. It’s basically like the better/worse mechanic from Dungeon World. It worked out really well because as mentioned there’s still always a chance of failure, rather than having stats and modifiers making it impossible to fail a particular roll.
I dig this. I’ve also explored 1d8+1d6 as an advantage.