Editing System grab-bags:Dice-based

[[System_grab-bags:Main_page|System_grab-bags]] > Dice-based Resolution Systems
=Dice types=
==Set dice==
Roll a specific die or set of dice for every action of a given type.
===Single die===
Roll a single, specific die. The number it turns up is your result.

Example: You roll a d10. It comes up with a 6. Your result is 6!

Example Systems; D&D
===Multiple dice===
The player rolls a set number of dice and combines the generated numbers. Generally, this is done by simply adding them together. 

Example: Roll 3d6. They turn up a 3, 4, and 6. Your result is 13.

Example Systems; GURPS
==EON style==

As explained by quoting_mungo.livejournal.com: ”Essentially, you roll three dice. Let's say you get 5,2,6. Remove the six. You have a total of seven. Now roll two more dice since you removed a six. Get 4 and 6. You have a total of eleven after you remove that six. Roll two more dice.  Etc until you get no more sixes. ”

Game examples: EON.


==Skill-based (Earthdawn)==

Roll a combination of dice depending on your skill.

Example: For instance, with skill 7 you roll 1d12, with skill 8 you roll 2d6, and with skill 9 you roll 1d8 + 1d6. With skill 100 you roll 4d20 + 6d10 + 4d8.

Game examples: Earthdawn.

==Median dice==

Roll three or more die. Use the median as the result.

==Multiple dice==

==FUDGE dice==

=Resolution Mechanics=
===Target Number===
Probably the most common mechanic in major games; a target number is established to which die results are compared. Many older games and most modern games use the Roll Over method of success, in which the generated number must exceed (or match) the target. Some games, especially older games like AD&D, used the Roll Under method where a roll which was less than (or equal to) the target indicated success.
Roll-Over; GURPS, D20, Star Wars, World of Darkness (variant).
Roll-Under; AD&D (ability checks)

===Non-Target===
Other types of resolution system are possible in which no target number is generated and success is determined by other features of the roll. Such resolution mechanics are generally idiosyncratic to the roll made.

==Roll Types==
===Target===
====Dice pool (Sorcerer style)====

The player rolls a certain number of dice. The GM also rolls a number of dice, depending on the difficulty of the task or the skill of the opponent. Both compare their highest numbers. The one with the lower roll loses, and all dice that the winner has higher than the loser's highest die are successes. If both players have the same highest die, set that die aside, and look at the next one. Repeat until there is a winner. 

Example: The player rolls 5 20-sided dice (4, 7, 9, 11, 12) and the GM rolls 4 20-sided dice (6, 12, 15, 18). The GM wins, with 15 and 18 being successes (since they're higher than 12, the player's highest result).

Game examples: Donjon (using 20-sided dice)

====Dice pool (Star Wars style)====

The player rolls a number of dice determined by their character and sums the generated numbers together. If the sum exceeds the target number, the attempt is a success.

Example: A character attempts a task with a target number of 15. For this task the character gets four, six-sided dice. They come up (3, 2, 4, 4), which totals 13, so he fails at the attempt.

Game examples: West End Games' Star Wars.

====Dice pool (World of Darkness style)====

The player rolls a certain number of dice. Each die that comes up with a number higher than the difficulty for this task contributes one success. The number of successes are then compared to the target.

====Number * die vs. target number====

The player rolls dice, and multiplies their result with some number. If the total is over some threshold (the ”target number”), the attempt succeeds.

====Number + die vs. target number====

The player rolls dice, and adds their result to some number (typically, the character's skill or attribute + skill). If the total is over some threshold (the ”target number”), the attempt succeeds.


===Non-Target===
====Dice pool (ORE style)====

The player rolls a certain number of dice, and looks for matches - dice that turned up the same number. If you roll 1,1,1,5,7,7 you have two matches, a 3x1 and a 2x7 one. The amount of dice is the width of the set, the size of the number itself is the height. Width indicates speed and competence, height indicates how favorable the circumstances were. In combat, for instance, the width would indicate how much damage you did and whether you hit the opponent first, and the height would indicate what part of the enemy you hit.

Examples: Godlike, Wild Talents, Reign.


=Minor variants=

==Accumulating bonuses==

On a successful roll, a player may choose to let the roll contribute a bonus to his next roll, instead of having an immeadite effect.

=== Extra bonuses===

In a number + die system, the contributed bonus is the amount by which the player succeeded. In a dice pool system, it is the number of successes.

=== Extra dice===

In a dice pool system, each success contributes one extra dice to the next roll.

==Bonus / penalty dice==

Roll more dice than usual. Keep the normal amount, choosing only the best (bonus dice) or worst (penalty dice).

Example: In The Shadow of Yesterday, you'd normally roll three dice and add their result. With two bonus dice, you'd roll five dice, and keep the three best. With two penalty dice, you'd roll five dice and keep the three worst.

==Bonus numbers==

Certain numbers on the dice contribute extra successes, or are considered to be higher than what they really are.

Examples: On an attribute + D10 roll, a roll of 10 is considered a 12. In a WoD-style dice pool mechanic, each dice turning up a number above 6 contributes one success and each dice turning up a 10 contributes two successes.

==Critical success / failure==

If a certain number is rolled, the task automatically succeeds or fails (usually in a somehow spectacular fashion), regardless of any other considerations. 

Examples: On a D100 roll, 1-5 are critical successes and 95-100 critical failures. On a 2D6 roll, two ones is a critical failure, with two sixes being a critical success.

===Botch dice===

If the ”failure number” is rolled, the failure is not automatic. Instead, a variable number of dice are rolled - the worse the circumstances, the more dice. If any of them turns up the ”failure number”, the task fails. The more failure numbers, the worse the failure.

Example: On an attribute + D10 roll, the player rolls a 0, indicating a possible failure. The circumstances give her three botch dice, so she rolls three D10s, which come up (4, 3, 0), confirming the critical failure (though only a mild one).
Game examples: Ars Magica

===Confirm the critical===

The success or failure is not automatic on rolling a certain number. The critical must be confirmed by making another roll: if that would have been an ordinary success, the roll was a critical.

Example: On an attack bonus + D20 roll, the player rolls a 19, indicating a possible critical. He rolls again, a 13, which combined with his attack bonus is enough to hit the enemy. This elevates the attack roll into a critical, dealing extra damage.

Game examples: Dungeons & Dragons, 3rd and 3.5th editions.

==Exploding dice==
=== Roll again===

On rolling a certain number, the dice may be rolled again, and re-rolled for as long as the ”exploding” number keeps coming up. Each roll contributes more to the total.

Examples: On an attribute + D10 roll, the player rolls a 0. She adds 10 to her total and rolls the dice again, coming up with another 10, after which she gets a 3 - netting a total sum of 23. In a WoD-style dice pool roll, the player rolls two 0's, which net him one success each and allow him to reroll them.

=== Roll again and multiply===

As above, but the ”exploding number” itself isn't added to the total - instead, each time it is rolled, it increases a multiplier that will be applied to the final roll.

Example: On an attribute + D10 roll, the player rolls a 1. She rolls again, and gets another 1, and another. Then she gets a 9. Since she rolled three 1's, the 9 is multiplied by 3 (or, as in Ars Magica, by 2^3 = 8). 

Game examples: Ars Magica.

==Extra effects==

If a certain number is rolled, the character manages to do something extra on the side, though the roll itself may still be a failure.

Example: On a D100 roll, 11s, 22s, 33s and so on produce an extra effect.

Game examples: Unknown Armies.

==Flip-flopping==

If using a method that generates a number with two digits, the digits may be exchanged, with 64 becoming 46 or vice versa.

Game examples: Unknown Armies.

==Roll and Keep==

Used for systems where one rolls a dice pool combined from two different sources (for instance, attribute + skill). The player rolls the amount of die given by the pool, but only gets to keep an amount of dice that's determined by one of the pools.

Example: Playing a character with Dexterity 3 and Firearms 4, the player rolls 3 + 4 dice. Of the seven dice rolled, she gets to actually keep four of her choice.

Game examples: Five Rings, 7th Sea.

==Wild die==