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The Genealogy of Advantage and Disadvantage in RPG Mechanics

This is inspired by a clear and informative blog post on iterative game design by Dwiz at his blog "A Knight at the Opera." (It's worth reading!) He demonstrates the development of "to hit" rolls from OD&D to the general mechanics of 5e by following the step-by-step redesign of those rules in successive editions. He closes by encouraging game rule designers with the words "Too many people try to reinvent the wheel, when they should be looking at other people's wheels for comparison."

My intention here is just to sketch the background of rolling with Advantage and with Disadvantage. It comes from outside of D&D. In D&D 5e, advantage and disadvantage mean rolling 1d20 twice and dropping the worse of the two (with Advantage) or dropping the best of the two (with Disadvantage) instead of making fine-grained judgment calls about how many plus and minus factors should affect a roll targeting a difficulty number (mostly arbitrarily assigned by the referee on the spot).

 My main point is that we have to look beyond D&D to find the origins of this mechanic whereby one rolls more than one die against a target number set by the referee and takes the better (or worse) result with the extra die. I see the roots reaching back nearly to the beginning of the hobby.

 Let's start with Tunnels & Trolls, 1975. Saving throws in that system were 2d6 (doubles add and re-roll) + Luck stat, aimed at target number set by the level of depth of the dungeon you were in. You had to beat 20 on the first level to make the saving throw, 25 on the second level of the dungeon, 30 on the third, and so on. This soon expanded to a universal saving throw system based on any stat, not just Luck. Feats of Dexterity used the same mechanic, but with DEX instead of Luck, etc. Furthermore, the Referee could easily ignore the physical level of the dungeon (not all adventures being in tiered dungeons or in dungeons at all), and just say "Make a level-2 DEX save," estimating the difficulty on the spot. (And that's how I actually played T&T with friends in the early '80s.) This became the main resolution system in the underrated RPG Mercenaries, Spies, and Private Eyes (1983).

Here we see the innovation of target numbers set by the referee on the spot, originally in terms of level of difficulty, moving away from an even more arbitrary and incomprehensible saving throw chart.

Next in my sketch is the influential game The Fantasy Trip (issued in parts 1977-1980). Here, from the beginning (the combat rules Melee published in 1977), difficulty of a task was not expressed by a target number, but by the number of d6 you had to roll to get equal to or under the relevant stat, which is the "low-roll target." A normal save was made with 3d6, against an average stat score of 10. But an easy saving throw required 2d6 for the same target, a difficult saving throw required 4d6 for the same target, a super-difficult one took 5d6... etc. (This is, by the way, the direct antecedent of GURPS, in which the number of dice is invariably 3d6, but complicated plus and minus modifiers are used instead. I like The Fantasy Trip's system better, in many ways!)

Here we see, I think for the first time, a universal RPG mechanic in which the number of dice called for by the referee expressed the difficulty of the task. In this example, with a roll-under mechanic, the more dice, the harder the task. (If, somehow, it had been a roll-over-target rule, then naturally it would be that the more dice, the easier the task--like 5e's Advantage rule.)

Our next stop is the Ghostbusters RPG (1986), seemingly an odd place for a major innovation, but the brains devising it were three of the giants of Chaosium: Sandy Petersen, Lynn Willis, and Greg Stafford (the people behind games like Call of Cthulhu and RuneQuest). In the Ghostbusters RPG, stats are expressed as a number of dice. Instead of rolling 3D6 to determine your Muscle trait, like the STR score of a D&D character, the trait itself can be 3d6 (expressed just as 3). You roll your dice and add 'em up against a difficulty number set by the referee on the spot. Starting to sound familiar to you players of later games?

Here, the more the dice, the better you are at it. That number of dice (rather than the fixed outcome of a number of dice rolled together, such as 3d6 per stat) is the character stat. The target number for the grand total still expressed something about the difficulty as estimated by the referee.

This is, as far as I can see, the beginning of what we might call "classic dice pool mechanics." The games that followed the path of Ghostbusters, like the Star Wars RPG (1987) and then the generic D6 System (1996), started here.

But we turn from the Ghostbusters RPG just three years later to Shadowrun (1989), a much more popular game than Ghostbusters over the years, but one that shows inspiration from the Ghostbusters RPG mechanics. In Shadowrun, your stat similarly indicates how many d6 you roll, but instead of adding them all up, you count how many "successes" your dice show per die. The number needed is set by the referee. Let's say you roll 5d6 (because your stat was 5) and the referee says you need a 4. Then the number of individual dice that equal or exceed 4 indicates the degree of your success. This is basically exactly what the original Vampire: The Masquerade RPG [1991] took over, but with d10 instead of d6. These "dice pool mechanics" would become very widely known during the World of Darkness game boom.

The idea of having more than one die each of which, separately and not as a total, gets tested against the target number, is another direct antecedent of the 5e Advantage/Disadvantage rule.

In 1992 there was Jonathan Tweet's and Robin Laws' game Over the Edge. To me, this was a huge breakthrough in character mechanics (wrapped up in one of the settings I have disliked, vehemently, for many reasons, more than almost any other setting, so I'll focus here on the mechanics). In this game, stats were basically descriptive. You say what you are, and that is your main "stat" (e.g. "Mad Scientist") and you add two secondary characteristics (say, "Debate Club Veteran" and "Computer Geek") and one flaw (say, "Sucker for pretty girls").  You undertake any actions related to your Mad Scientist "main stat" with 4d6, actions related to your secondary characteristics with 3d6, and other regular stuff with 2d6. You add them up and aim for a target number set by the referee. (I'm sure I'm leaving out relevant details, but that's approximately it.)

But additionally, the Referee can decide if circumstances are favorable or not. If favorable, the character can add a bonus die and drop the worst one. If not, then roll an extra die and drop the best one.

This is basically 5e's Advantage and Disadvantage, right there in 1992. I can't think of or don't know of an earlier version of this, but it may be out there--unless it's The Fantasy Trip, where the number of dice rolled indicates level of difficulty (but there is no dropping of dice either way).

Anyway, the main point: Advantage and Disadvantage dice are (as should be obvious if you think about it) a riff on dice pools. It is, in effect, a simplified dice pool with no adding of numbers needed, as in Shadowrun. These rules existed for many years before 5e made the rule canonical and widespread. It entered the stream with one of the "indie games" of the '90s written by two of the most innovative designers of that period.

Advantage and Disadvantage, as used in 5e, are fun because they cut out lots of on-the-spot calculations of bonuses and penalties that pile up into a huge stack as characters advance. Advancement is already rewarded by more plusses and minuses that have the side-effect of slowing the game down.

In summary:

I find the roots of target numbers set by the referee on the spot in the saving throws of Tunnels & Trolls, starting 1975 (with exploding dice on doubles).

I find the dice pool mechanic where number of dice interact with difficulty rooted in The Fantasy Trip, starting 1977.

I find the dice pool based on player character stats in the Ghostbusters RPG in 1986.

I find the idea of "target number per individual die" in Shadowrun, in 1989.

I find the basic idea of Advantage and Disadvantage (extra die, drop best or worst) in Over the Edge in 1992.

Here, as in many other areas, the history of D&D cannot be extricated from the history of the hobby as a whole. In conclusion, as Dwiz says in his post that inspired me here today, "Iterations aren't always linear"!


  1. The idea of rolling several dice and dropping one to find a total shows up in AD&D in the Dungeon Master's Guide (published 1979), as a method of generating character statistics. Also, the idea of rolling two dice and taking the higher shows up in Magic Realm (also first published 1979) as a method for determining almost all results, though it can be affected by special abilities, magic items or spells, and so on, usually by one or more of: a) rolling one die instead of two, b) controlling the result of one die, or c) adding or subtracting 1 from the higher die result.

    1. Thank you for this contribution! I had Magic Realm (a very unusual board game at the time, I think). I don't remember that specific dice rule, as it was an exceedingly complex game with lots of bits interacting. All those different chits and cards and that big book of rules...!

      About stat generation, yes, I am aware of that D&D option to roll 4d6 and drop the lowest to generate stats. That isn't the same as resolution of actions, but you are right that dropping a die was a known (and sometimes debated) mode of character generation. I still think that 5e's Advantage/Disadvantage system owes more to the dice pool idea in wide circulation than to these indisputable early antecedents for the concept of dropping a die.

    2. I think that Over the Edge took its inspiration from the AD&D procedure. If you're right about its place in the history of developing that mechanic, then I am certain that it does go back to the AD&D procedure, and from there to whatever inspired Gygax to write about it. I suspect that "roll 2 dice and take the higher/lower" can be found in some set of wargaming rules in the '60s or '70s, probably the latter as that would explain why a similar but not the same mechanic shows up at the same time in two different games.

    3. Also, I am reminded that the Space 1889 (released 1988) RPG used a dice pool mechanic that involved either taking the highest roll, taking the number of dice that met or beat a target number, or taking the total of the dice pool, depending on the specific sort of situation. There was an additional mechanic of just rolling one die and trying to hit a target number, but that's not really relevant to this timeline of development.

    4. I think you are right that the "drop a die" either for better or for worse antedates RPGs.

      Space 1889, now there's a game I haven't though of in a long time. One of the many for me in the category of "owned it, never got to run it, gave it away long ago." I can't remember anything about the dice rules in that game, but it sounds like it fits right between Ghostbusters and Shadowrun.

      Thank you!

  2. Interesting post as ever. I think there may be a significant missing element, though: Jervis Johnson's Blood Bowl (1986). That game uses a fully formed advantage/disadvantage mechanism for blocking and blitzing. If the attacker has a higher strength score than the other in such situations, that character's player rolls two dice and picks the best. If the attacker is weaker than the defender, the attacking player rolls two dice and the defending player picks the most favourable. And if one figure's strength is double the other, the best (or worst) of three dice is picked.

    Blood Bowl uses dice with symbols for different outcomes, so in these situations, the 'best' outcome may vary (knocking a player down versus pushing him into the crowd, and so on). But the mechanism is fully developed 28 years before 5e.

    As you know, Games Workshop was an RPG company back then, which led to plenty of crossover between RPGs and miniature games. Blood Bowl also had a tremendous following - so much so that the game was kept alive throughout the long period when it was out of production. It's certainly been a big influence on other miniature wargames. One might note that GW tends to keep its 'perfect' game designs - such as Blood Bowl and Space Hulk - out of production for long periods - presumably because they can't be used to sell new miniatures in the way that its more open-ended wargames can.

    The thread you identify linking Tunnels and Trolls and The Fantasy Trip is interesting. I've seen the kinship between the games expressed in a couple of places, and I think Steve Jackson was involved in some early T&T products. The two games also shared an illustrator in Liz Danforth.

    One thing that's struck me as an enticing possibility is a combined T&T/TFT game, in which mass or general combats are resolved using T&T's rules and particularly important or tactical fights use TFT's hexes. I'm not sure how one would go about synching the systems and carrying over the attrition from one to the other (perhaps using TFT's weapon stats throughout would be a start), but there might be something there ...

    1. You're right about Steve Jackson and T&T. Jackson is credited with developing *Monsters! Monsters!*, the T&T variant of 1976 in which players play the bad guys. Danforth illustrated that. I assume these folks go way back together, at least to those days. Danforth's illustrations are (in my view) the only good ones in the re-release of TFT.

  3. Ah - I see I've overstated things by eight years: the blitzing and blocking dice came in in 1994 with the third edition - so it was only 20 years ahead of 5e. Still, the point stands.

  4. And - one more thing - if we can see fully fledged advantage/disadvantage in third-edition Blood Bowl (1994), there's a "take the best" dice-pool mechanic in Space Hulk (1989). When a marine shoots, he needs a six on either of two dice. And when a genestealer attacks, it needs a six on one of three dice. That's closer to advantage/disadvantage than Shadowrun, I think, and presumably an ancestor of, or influence on, the later Blood Bowl mechanic.

  5. And - sorry! - one further point on Space Hulk (1989): although its combat system is fixed (genestealers roll three dice in melee, marines roll one die, etc.), it is essentially a fully formed advantage system. The basic combat system for shooting or hand-to-hand fighting, is "roll dice and kill on any six". Regular marines roll two dice when shooting.

    But when it comes to hand-to-hand combat, genestealers have a great *advantage* and so roll *three dice*, taking the best. Marines are *disadvantaged* in close combat and so roll just one die.

    So, if we look at the standard shooting attack as the basis of combat in the game, we can see close combat as an advantage/disadvantage extension of that. Advantage works in exactly the same way as 5e D&D whereas disadvantage works differently, because rather than taking the worst result (as in Blood Bowl), you lose a die from the base pool of two.

  6. I like all your points about Blood Bowl (which I didn't play) and Space Hulk (which I owned and played). I hadn't considered those. (Those games were not nearly as popular in the US as in the UK, I think.)

    Take a look again at the TFT Melee Shield Bash rule and the Blood Bowl blocking and blitzing rule. They both vary number of dice depending on relative Strength stat of those in the collision. Interesting!

    I'm not sure if I'd consider genestealers' higher dice pool in melee as "advantage" in the same sense (beyond the literal sense), but I agree that the line is a blurry one. The difference between getting an extra die, with the requirement that any one die rolls a "success," and the 5e Advantage/Disadvantage system, is pretty much a matter of perspective. That's why I think of the 5e system as an offshoot of dice pool mechanics.

    You definitely have added to the main point here. The hobby field of gaming has different compartments that overlap, and practices that seem marginal or idiosyncratic can become mainstream in time, especially when they are integrated into the most popular games.

    I wonder what marginal practices of today will be integrated into the most popular games of the future.

    1. Yes, that's a good spot on the shield bash - and the rules are modelling a very similar situation too, though the dice are used in a kind of mirror-image way (defender rolling vs attacker rolling).

      The marginal RPG practice that deserves to become popular, I think, is Into the Odd's use of small "starting packages" for adventurers (e.g. "pistol, grease, hand drill, drum"). At a stroke, that cuts away a swathe of 3d6 x 10gp tedium in character creation *and* fuels the sort of in-game Heath Robinson invention on which the best RPGs thrive.

    2. I think a lot of the independent and creative amateur new games have starting packages. Some of them now have tables and one rolls for some random gear at the start instead of browsing the generic shopping list.

      It reminds me of the original Warhammer FRP, which, unless memory fails me, included such gear according to profession. That's how it works in my home rules, too (speaking of amateur).

      I think some old D&D modules included starting equipment kits. I agree with you that it's a great idea.

  7. This is a very interesting topic. Please allow me to contribute by raising another point that might be of interest.

    The oldest instance of rolling 2d20's and keeping the best result was one of the maneuvers added in the Tome of Battle in the tail end of 3.5. Namely the Shadow Blade technique.

    "As part of this maneuver, you make a single melee attack against an opponent. Unlike on a normal attack, you roll 2d20 and select which of the two die results to use. If you use the higher die result, resolve your attack as normal. (Your mystic double misses, but your true attack might hit.) If you use the lower die result, or if both die results are the same, your attack deals an extra 1d6 points of cold damage as both the mystic double’s attack and your true weapon strike home."


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