Duodeca RPG System

This is the overview page for Duodeca, a WIP tabletop roleplaying system. It was initially built to run the Fallout: Emerald City campaign setting but (with some tweaks) it'll ideally be adaptable enough to use for a variety of games.

Basic mechanics

Duodeca is named for its primary dice mechanic, 2d12. The vast majority of rolls are permutations thereof. 2d12 strikes a balance between the classic 1d20, with a flat curve of probability (all 5% likely) which thus tends to be 'swingy,' and 3d6 which is more heavily curved. Under certain circumstances advantaged or disadvantaged rolls are made, these are 3d12 but taking only the highest pair or lowest pair of dice.

Characters are built of attributes (Strength, Agility, Endurance, Intelligence, Perception, and Charisma) and skills rather than classes. This is to encourage characters existing as distinct individuals rather than fill-in-the-blank archetypes. The choice of attributes is derived from the Fallout games but minus Luck due to it operating on a more metaphysical level rather than illustrating the tangible capabilities of a character.

Duodeca uses a level system (1 to 12) for character progression.

Character creation

Attributes range from 1 to 12. To create a character, begin by assigning them their attribute scores using a pool of 36 points.

Characters have 12 + INT skill points at first level, then 4 each subsequent level.

Characters have 1 perk at first level, then 1 perk each subsequent even-numbered level.

Characters have 8 + END health points at first level, then 4 + ENDmod health points each subsequent level.

Characters have 8 + CHA morale points at first level, then 4 + CHAmod morale points each subsequent level.

Skills

Skills range from 0 ranks to 24 at maximum.

Tactical play

Initiative and turn order

Combat initiates with rolls from all participants to determine turn order, called the initiative roll. This is 2d12 + PERmod; any ties are resolved by who has the higher PER. Participants who enter the combat later roll initiative and slot into the turn order based on that.

Actions and reactions

Every character can perform three actions and one reaction per round. Actions can only be performed in that character's turn in a round, reactions can only be performed during another's.

Armor class, damage threshold, and cover

A character's armor class is 16 + AGLmod + PERmod at base. Armor can increase it, as well as taking cover in combat.

Miscellaneous mechanics

Recovering health and morale

Health points can only be regenerated by healing items, medical attention using the Medicine skill, or extended downtime. Morale points can only be regenerated by resting. Thus a stimpak restores health but not morale while a short rest restores morale but not health.

Carry weight and encumbrance

A character can carry up to 30 + 5(STR) lbs without difficulty. Past this threshold they enter light encumbrance, where movement requires two actions to move the distance of one. Heavy encumbrance begins past 1.5(30 + 5(STR)) lbs, whereupon movement requires three actions to move the distance of one. It is impossible to carry more than 2(30 +5 (STR)) lbs.

Statistics

The average result of a 2d12 roll is 13. With advantage the average is 16 and with disadvantage 10.

The theoretical maximum skill bonus one can reach is +27, and the maximum roll is 51.

The theoretical maximum health/morale at Level 12 is 97, and the minimum is 31.