Here’s what I’m imagining the “Resolution Methods” section might look like:
The most common resolution method, this describes rolling a single d20 and then adding modifiers of various kinds. The goal is usually to roll higher or lower than a specific target number (Roll-over vs Roll-under). With roll-over resolution, the target is usually set by the GM or some fixed value (i.e. 12 or 15). With roll-under resolution the target is usually a character ability score or other innate value.
Roll-under resolution is used in Into the Odd by Chris McDowall. In that game, to make a Save players roll 1d20 under their STR, DEX, or WIL score (generated by rolling 3d6). Tom wants to succeed on a DEX save to avoid a falling boulder. He rolls a 14, which is higher than his DEX score of 12. He fails.
Modifiers can be simple or complex. The classic form is converting ability scores into a numerical modifier i.e. a score of 10 is +0, a score of 8 is -1, a score of 12 is +1 etc.). More complex modifiers include advantage and disadvantage (rolling another number of d20s and taking the highest/lowest result) or boons and banes (rolling an additional number of d6s and adding/subtracting the highest).
Boons and banes were introduced in Shadow of the Demon Lord by Robert Schwalb. For example, if Tabitha were to make a d20 roll with 2 boons, she might roll 1d20 (17) + 2d6 (4 and 2). She then takes the highest d6 result (4) and adds it to the d20 result (17) for a final result of 21.
One interesting note to consider is that static modifiers change the probability range of the d20 roll. For example, a d20 ruleset with +1 modifiers means that on some rolls characters cannot have a final result of 1 with their roll and can only receive results between 2-21. The boons and banes system adds further complication by expanding the probability range from between -5 (1-6) to 26 (20+6). In contrast, advantage based systems do not share this characteristic: even if you roll with 5x advantage, the highest score you can achieve is still 20.
Target 20 is an extreme version of roll-over 1d20 resolution where only rolls over 20 indicate success (hence the name). This higher target number is usually justified by adding character level to the roll.
2d6 rolls, sometimes known as skill rolls, are a common alternative to 1d20 rolls. The 2d6 roll introduces a bell curve between the probability range of 2 and 12, making results in the range 7-9 much more likely than a 2 or a 12. This means that results are much more predictable and a small bonus of +1 matters much more. Advantage and disadvantage in 2d6 systems usually requires rolling 3 or more d6 and picking the highest/lowest 2.
2d6 rolls are used in Stars without Number by Kevin Crawford. To make a skill check with a bonus of +1, Wenqian rolls 2d6 (8) and adds +1, giving a final result of 9.
It should be noted that, besides using 2d6, the same questions of roll-over/roll-under resolution from 1d20 resolution still apply.
Possibly the simplest resolution system, the player rolls 1d6 and compares the result to a number. If the result is less than or equal to the number, they succeed. This is roll-under resolution with a d6.
Opposed resolution means that the GM and the player both roll some amount of dice and the highest result wins, usually with some negotiation on a tie. In Free Kriegspiel Roleplay circles this is customarily 2d6, enough to be regular without too much predictability. In other games, the dice both sides roll may be imbalanced to symbolise advantages or disadvantages on the part of the player.
Jeff and the orc are wrestling for a magical goblet. Jeff and the GM both roll 2d6, with Jeff rolling 12 and the GM rolling 7. Jeff wins, grabbing the goblet.
The most basic resolution method, this method of resolution relies on the GM and player coming to an agreement without consulting dice or oracles. This can be the most unfair-seeming resolution method given the imbalance of power between player and GM, but can also (in a setting with a high level of trust) produce the most realistic or satisfying results.
Some common types of discussion include Matrix arguments, where the party forwarding an argument must give three justifications, which if challenged themselves must have three justifications etc. Others include pro/con lists as well as simple plain language establishment of fictional positioning.
Mark is attacking a dragon. He states that he should be able to harm it (using a Matrix argument) because:
- His sword is sharp and can cut dragonscale
- He is small and can attack the dragon’s weak belly (Halfling)
- He can run quickly and dodge the dragon’s blows (DEX 18)
The referee challenges Mark on the first count. He then provides three justifications for the sword:
- The sword has been well-polished
- I’ve fought dragons before and know how to attack them
- The sword is Grimfang, the Dragon’s Bane, slayer of 10 dragons before this generation
Satisfied, the ref allows Mark to proceed with their attack.