Wednesday, March 10, 2010

Target Number versus Difficulty Die

Back in August I mentioned that the first person to use a set of different polyhedral dice for a role-playing game was David Wesely.

Most RPG systems measure the difficulty of a skill attempt with a number. The player rolls dice (usually modified by some character sheet bonus) and attempts to roll higher or lower than that target number. I mentioned two examples recently.

I have long wanted to create a workable rules system in which character skill was measured by polyhedral die type, not a numerical rating. I pictured the character sheet having a row of little check-boxes for each skill (d4, d6, d8, d10, d12, d20) that would get shaded in as the character increased in skill.

However, this simply does not work well when the difficulty of an attempted action is rated with a target number. There is too much difference between a d4 and d20.

Last December I finally realized what needed to be done. Instead of target numbers, rate the difficulty of an attempted action with the same set of six polyhedral die types. For example, a very easy task would have d4 difficulty and a nearly impossible task would have d20 difficulty.

The success of the skill attempt is thus the amount by which the skill's die exceeds the difficulty's die. The gulf between the d4 and the d20 is pleasantly bridged. Someone with minimal skill attempting something nearly impossible could get lucky and roll higher on the skill's d4 than the difficulty's d20, but it would be appropriately rare.

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