text: The Earthdawn game system pioneered "step die mechanics" through the use of its action step table. Generally speaking, a low skill is represented by a low die size, and a high skill is represented by a high die size. The Earthdawn table lists combinations of dice that are expected to produce average rolls from 1 to 40, and is used for almost all die-rolling in the game. The western-horror RPG Deadlands and The Window also make use of similar step die mechanics, although low abilities in The Window are represented by higher die types.
  The fantasy-cyberpunk RPG Shadowrun and White Wolf's Storyteller System (most prominently used in Vampire: The Masquerade) both use a "success test" mechanic, whereby the player rolls a certain number of the same kind of die (d6 in Shadowrun, d10 in Storyteller), and only the dice that roll higher than a certain number are counted towards a successful test.
  A number of game systems allow for "critical" successes and failures ("crits" in shorthand). The effects of critical die rolls vary by system and by gamemaster but typically result in multiplied or maximum effectiveness for the action being attempted in the case of a critical success and reduced or minimal effectiveness in the case of a critical failure. A critical success (in combat, a critical hit) occurs when the die roll yields the highest possible number (a 10 on a d10), while a critical failure or fumble (in combat, a critical miss) occurs on a roll of a 1. Systems in which low rolls yield a higher chance of success may reverse the system, with a 1 being a critical success and the high roll being a critical failure. Fanmade critical hit and fumble tables are especially common in Dungeons & Dragons; in these homebrew rules, critical rolls are frequently lethal on hits and crippling to the attacker on fumbles. In the Storyteller System, each 1 rolled cancels out a success; if the player rolls one or more 1s and no successes, the character "botches" the action being attempted. In some interpretations of this rule, a botch occurs whenever a player rolls more ones than successes.
  Several game systems allow dice to "open-end", whereby if a die shows the highest value, the player may roll the die again and add- sometimes without limit. Usually, the game system uses colorful lingo to describe this mechanic: In the swashbuckling RPG 7th Sea, dice "explode"; in Deadlands, such a die is said to be an "ace". In the Storyteller System, this is called the "ten-again" rule.
  The new d20 System bases most rolls around a 20-sided die, which allows for more nuances than a six-sided die, though some systems (notably, the White Wolf d10 system, and the Shadowrun d6 system) find ways to generate rich results with other dice. Roleplayers often debate which system is "best", as different systems have varying degrees of simplicity, realism, game balance, and randomness.
  Some role-playing gamers also use tops to augment dice in generating randomized results. A typical deck of cards, sans face cards, with red high and blacks low, may be used to generate random numbers from 1-20. Other random generation systems are used, for variety, but for effectiveness either dice or electronic solutions are standard.
  Some people believe that dice can be used for divination. Using dice for such a purpose is called cleromancy. A pair of standard 6-sided dice is generally used.
  Astrological dice are a specialized set of three 12-sided dice for divination, using the concepts of astrology and containing astrological symbols for the planets, the zodiac signs and the astrological houses. The first die represents planets, the Sun, the Moon, and two nodes (North Node and South Node). The second die represents the 12 zodiac signs, and the third represents the 12 houses. In simplified terms, the planets, etc. could represent the 'actor'; the zodiac signs could represent the 'role' being played by the actor; and the house could represent the 'scene' in which the actor plays.