DGRPG Design Diary #7: Core Mechanics Review

A quick recap of the core mechanics, with some provisional values.

Task Resolution:

The central task resolution mechanic used to determine success or failure. This can apply to setting or disarming a cunning trap, jumping over an obstacle, climbing a rope, attacking an adversary, intimidating a subordinate, whatever.

d20 + modifiers vs. target number

I'm going to try and keep the range of modifiers pretty tight to avoid undue inflation as characters improve over time.

Modifiers

Attribute modifiers are derived from the PC's Attributes, and use the Attribute most relevant to the task at hand. Such modifiers are kept deliberately low to reduce the emphasis on number-crunching character optimisation by ensuring that even a character with non-optimised Attributes remains playable.

Attribute	3	4-5	6-8	9-12	13-15	16-17	18
Modifier	-3	-2	-1	0	+1	+2	+3

Equipment modifiers are conferred by special items, weapons, etc. An enchanted dagger might grant a +1 modifier to damage inflicted, an enchanted helm might grant a -1 modifier to damage received. Such items are likely to be rare and highly prized.

Situational modifiers are conferred by environmental factors which help or hinder the performance of a task - a PC might enjoy a positive modifier if assisted by companions, given extra time to perform the task, or similarly favourable conditions; correspondingly a PC might suffer a negative modifier while on fire, or in pitch darkness, or hanging by one leg from the ceiling, or likewise distracted. It is entirely possible (and indeed encouraged) to seek advantage by inflicting such negative modifiers upon adversaries.

There is a limit to the number of modifiers that can be applied to a task resolution attempt to keep things from getting silly - three modifiers or a total of +5 in each direction, whichever is lower.

Target Numbers

Target numbers vary based on the difficulty of the task at hand. To succeed at a task the total of d20 + modifiers must exceed the target number. Dice should only be rolled when there is a likelihood of failure having consequences - so hopping over a puddle of water wouldn't require a roll, but leaping a bottomless crevasse (or a puddle of acid) would.

Difficulty	Target	% success
Trivial	1	95%
Easy	5	75%
Standard	10	50%
Taxing	15	25%
Daunting	19	5%

The default target number is 10, which gives a 50-50 chance of success or failure for an individual of average ability. This can vary according to the task - jumping over a 3' gap might be Trivial, a 5' gap might be Easy, a 10' gap Standard, a 15' gap Taxing, and a 20' gap Daunting.

I've also been made aware of a game called Dungeon World which uses a "partial success" mechanic - such that borderline task resolution rolls might succeed, but with a cost or consequence. It's an idea that's intriguing to me, so I'll be researching it further.