In table top RPGs, resolution mechanics refer to the way that the games rules decide the outcome of events within a campaign's narrative. For example, Fighter Fred is swinging a sword at an orc. Does the swing connect? Fred's player rolls a d20 and it comes up 9. Fred's melee attack bonus is +7 which added to the roll is 16. This beats the orc's armor class of 12 and Fred hits. Roll for damage.
Resolution mechanics are a core part of table top. Starting with Original Dungeons and Dragons and going forward nearly every game system has used dice in some fashion or another. It's often the resolution mechanic and the way it interfaces with other systems that give a particular RPG its character. Taking the d20 system from above for example the typical task resolution goes like this: roll a d20, add and/or subtract modifiers to the roll, compare the final number to AC or difficulty class. If the modified roll is greater than or equal to the number the action succeeds; if it's less the action fails. Other systems take the roll in the opposite direction. In GURPS players roll 3d6 and if they roll at or under the target number it's a success and over that number it's a failure. A d20 creates a flat distribution over twenty outcomes while 3d6 create a smaller normal distribution meaning that a +1 in GURPS is worth significantly more.
Most game systems can be grouped into families based on the resolution mechanics they employ. Call of Cthulhu and RuneQuest are a system where players want to roll a 1d100 at or under their character's skill rating which can be modified up and down to reflect difficulty. Vampire: the Masquerade uses dice pools of d10s where reaching or exceeding a target number on any of the dice grants success and the number of dice over that number establishes the magnitude of the success. Powered by the Apocalypse games use 2d6 plus or minus a stat with a static roll over a target number of seven for a partial success and ten for a full success. Each game system provides a clear rules delineation between success and failure while providing very different experiences of what that success means. It's my impression that any resolution mechanic that you can devise and which is actually playable has probably already been implemented somewhere. There are diceless systems that use cards and other even more esoteric options for randomization. As a general design principal no outcome should ever be completely impossible. The most powerful characters can always fail even the simplest tasks and vice versa in the extremity of probabilities. While the ideal for game systems is that they fade into the background and the collectively envisioned narrative holds players' attention the reality of constant dice rolls make a simple, dynamic, and fair resolution mechanic one of the most important features of any RPG.
IRON NODER XIV: THE RETURN OF THE IRON NODER