Nuts & Bolts #6 - Decisive Trundling

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Special dice rolls. From the 1-in-20 chance at a critical hit and critical failure, to more complicated mechanics like exploding dice, advantages and threats, and minor or major effects.  Nearly every RPG that uses dice has some kind of mechanic around special dice results. 

Whether the effect results in double damage, an increased effect, or simply managing a nigh impossible task the grandfather of special dice rolls, the natural 20, is a universal symbol of success.  Conversely the "1" is a universal failure, and often elicits groans from all involved, not just the player who rolled the die.

But what are the pros and cons of such mechanics?

Let's start with the most simple fact: critical hits are fun, and critical fails are often memorable, and almost always interesting. Nobody can argue those facts, and being that the point to the game is to have fun that's reason enough to retain these kinds of mechanics. A well timed 20 can boost moral, or swing the tide of an encounter for the PCs.  A 1 in the hands of the GM can likewise be cause for celebration, while in the hands of players the unfortunate incidents often become the stuff of legend.

Not all games use the venerable d20 for their base mechanic. The Stunt mechanic used by Dragon AGE, and discussed in a prior column, is one such mechanic.  The complex symbol based dice mechanic of Fantasy Flight's Star Wars games determines not only success and failure of an attempted task, but also Advantages and Threats that can further color the outcome of each roll.  This system could fuel a column of its own, but suffice to say that it leads to each roll having a strong narrative impact where failures can have a silver lining, and success can be tainted by unforeseen complications.

Somewhat more simply, White Wolf's games use dice pools and d10s, depending on the specific game 10s can count as multiple successes or follow the "exploding" rules where you count them as success and then re-roll the die (or add a new one). Ones acted as part of a critical fail mechanic, working against successes in one version, while in others they only activated when no successes were rolled on the dice. Mechanically exceptional numbers of successes improved the effects of the action undertaken, while "botches" worked much as other critical failures.

The flip side of all this however isn't always nice. Let's look at the impact on game and encounter balance.  While it could be said that the GM should not call from a roll if success (or failure for that matter) could impact the story, there are plenty of times when the dice need to be rolled, and sometimes those rolls can go awry. Under normal circumstances these kinds of rolls are bounded by chance; probability suggests that a 20 comes up as often as a 1 for instance, and that those rolls on a d20 only occur 10% of the time.

Of course these things come to the table and ... go right out the window.  Every gamer has stories of those times when die rolled multiple 1s in a row, or when a series of spectacular hits turned a climax into an anti-climax.  Things skew worse when dice rolls occur on both sides of the table and skew in opposite directions. A routine encounter becomes truly difficult, or a complete pushover.  These events are reasonably rare but they can screw things up for players and GMs alike.

All this also means that balanced game encounters don't always survive contact with special dice results. That's hard on GMs who have to either figure out how to not kill their players, or scramble to rescue a session from anti-climax.  Likewise it's hard on players at least half the time, bad dice rolling leading to character death or ignoble defeat is not terribly fun, and for some a combat that goes too easily by way of good dice rolling is often just as anti-climatic.

Referencing back to my second column and the one-sided dice rolling of the Cypher System, I feel that having such a mechanic can help to level off the swings of fortune and chaos, and keeps the special rules in the hands of players (where they are nearly always most interesting). Similarly mechanics where special results are either graded (e.g. ranging from very minor, to rather significant), and/or occur more frequently (possibly on every roll) will help to even out and level off the potential for extreme swings in luck.

Regardless of your preference for these mechanics, a degree of exceptional results can help to drive engagement of the players and instill excitement and uncertainty to dice rolling, all of which are good.  Something to keep in mind is the balance of that equation, and how good mechanics can go awry if poorly balanced.