Criticize This

Roll 3d6 to generate attribute values; range of 3-18. Range of 1-10 for skill values, added to attribute. Full range from 3-28.

Innate challenge of task represented by Difficulty, a number from 1-5 representing how many dice you roll. Range of outcomes is 5-30, however even on Difficulty 5 the average result is 17.5.

Circumstantial challenge of task represented by Modifier, a positive or negative adjustment to the die result. This is stuff like "it just rained so it is a little slick" or "you have really good tools here, so it is easier than it might have been".

Roll under.

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So...

If attribute value is 15 and skill value is 4, total is 19.

If Difficulty is 3 and Modifier is +3; 3d6+3 must be less than 19 in order to succeed.



Possible problems with this system?

As I see it, it allows the GM / module designer to custom tailor the odds of success failure pretty well. Lots of randomness, but it isn't perfectly distributed like on a d20. You are just as likely to roll a 20 as a 10 on a d20. But multiple sixes have a bell curve distribution, thus the randomness is more likely to be dramatic and unexpected, I would think.