The Bay City Adventures
One Roll Engine
The One Roll Engine (ORE) is a system by which complex actions can be resolved using a single die roll. A player rolls a number of ten-sided dice (never more than 10) called a “pool,” often determined by a kid’s Abilities and Skills or by the power of a monster’s body parts, and hopes to roll a matching set of numbers. Most basic rolls can be declared successful if a set is rolled, regardless of the details. However, when more information is needed, a set can be described by two characteristics:
Height: The value rolled in a set. A set of two 8s is higher than a roll of three 5s. Height usually indicates precision of a roll. In attack rolls, height indicates hit location.
Width: The quantity of dice in a set. A success of three 5s is wider than a roll of two 8s. Width usually reflects the speed and power of a roll. In attack rolls, width indicates damage.
Depending on the circumstances, a player may prefer to roll wide or high, though generally Height is the gauge of quality of success. For example, difficult actions may require a certain minimum height to be rolled.