One Roll Engine (ORE)

"The One-Roll Engine (or O.R.E.) is a generic role-playing game system developed by Greg Stolze for the alternate history superhero roleplaying game Godlike. The system was expanded upon in the modern-day sequel, Wild Talents, as well as the heroic fantasy game Reign and the free horror game Nemesis. The O.R.E. gaming system is notable for its unique dice rolling system where matched values on ten-sided dice (d10s) determine all necessary combat information like initiative, hit location and damage all in just one roll.

Mechanics

The O.R.E. system uses a dice pool of d10s equal to the character's Stat and Skill similar to that used by Storyteller system, but the method to determine success is different. In the O.R.E. system, success is determined by die result matches, such as a pair of 8s. The Width of a roll, the number of matching dice, determines the speed (and damage, if in combat) of a roll, while the Height of a roll, the face up result on the matched dice, determines how successful an action was and location of a hit in combat. Shorthand notation for writing results is Width x Height, so a pair of 8s would be written 2x8 and three 2s would be written, 3x2.

Two special types of dice also come from Talent Powers, Hard Dice, which are considered to always have a value of 10, and Wiggle Dice, which the player can assign any die result to after the roll. The shorthand notation for Hard Dice is hd and Wiggle Dice is wd, so a Dice pool of six regular dice, two Hard Dice and one Wiggle Die would be noted 6d+2hd+1wd.

NEMESIS introduces Expert Dice, which may be used as normal dice, or the player can to select their value before the roll, but no two Expert Dice can be selected to have the same value. Expert Dice are also used as buffer against die penalties, where each Expert Die counteracts one die penalty, but then must be rolled as a normal die. NEMESIS also renames Wiggle Dice to Trump Dice. The shorthand notation for Expert Dice is ed and Trump Dice is td.

In Reign the "Wiggle Dice" were renamed to "Master Dice" (shorthand notation "md"). In this setting any dice pool just could contain one special die ("md" or "ed") and can never exceed ten dice."

Source: Wikipedia, "One-Roll_Engine", available under the CC-BY-SA License.