DoubleZero: Core Mechanic

February 17, 2010 6 comments

All characters have five Attributes rated on a scale from 1 to 15, with 1-5 being a poor rating, 6-10 being within the range of human average, and 11-15 being exceptional. Characters also have Skills rated from 1 to 15, with the same levels indicating poor, average, and exceptional ranges.

Each Skill has an associated Attribute. The Attribute and Skill ratings are added together to determine the Skill’s base chance, a number from 2 to 30.

The gamemaster determines how difficult a task is to perform, and assigns an Edge Factor to reflect the character’s advantages in performing the task. This is on a scale from 1 to 10, with 1 reflecting the least advantage/hardest to accomplish, 5 being average, and 10 showing the greatest advantage/simplest to accomplish.

The player multiplies the Base Chance by the Edge Factor to determine the Target number. Don’t worry, there are tables for this and they’ll be included on the character sheet. If your Base Chance is 20, for example, and the Edge Factor is 5, the Target number is 100.

Roll percentile dice, which are two 10-sided dice with one die representing 10′s and the other representing 1′s. If you roll a 7 on the 10′s die, for example, and 6 on the 1′s die, you’ve rolled a 76. The goal is to roll under the Target number. A roll of 01 always succeeds. A roll of 00 always fails.

Most competent characters will succeed most of the time. What is more important is the degree of success, called the Quality Result. Did the character barely make it, or did something spectacular just happen? Interpreting what the Quality Results means in the context of the scene is one of the things that makes DoubleZero more than just a nuts-and-bolts tactical game and offers opportunities for storytelling. Quality Result is determined by what you rolled in comparison to your Target number. If you rolled under 10% of your target number (for instance, if your Target was 70 and you rolled under 7), that’s an Excellent success, the best you can get. If you roll under 20% of your Target (you needed 110, and you rolled less than 22), that’s a Very Good success. If you roll less than 50% of your Target (you need to roll 130, and you rolled less than 65), you scored a good success, better than average. Anything from 51% to the Target number is average. Again, don’t sweat the math, there are tables for this and they address rounding issues as well.

Those are the basics. Everything builds from there. If nothing else, remember that you’re rolling percentile dice and you always want to roll low.