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Actions by Attribute

A streamlined way to determine character success

Every RPG has a mechanic for determining the outcome of attempted actions, but some are more handy than others. The Chimera Action Roll mechanic is a quick-and-dirty method that takes realistic inputs and provides—with minimum fuss—outcomes that make sense. Best of all, the system is basic and flexible enough to apply to just about any RPG system.

Character Attributes

The Action Roll system is based on character attributes, which determine the difficulty (and corresponding d20 target number) of any meaningful action that your character attempts. For example, your character’s strength determines how hard strength-related actions are, intelligence determines the difficulty of intelligence-related actions, and so on, for all attributes in your system.

Chimera uses six attributes, which are fairly broad and easily mapped to other systems:

  • Strength (STR): Physical might and brute force
  • Intelligence (INT): Intellect, memory, and mental aptitude
  • Willpower (WIL): Resolve, faith, and strength of will
  • Dexterity (DEX): Agility, handiness, and deftness
  • Constitution (CON): Fitness, stamina, and overall health
  • Charisma (CHA): Influence and leadership

Attributes are assigned as Primary, Secondary, or Tertiary, representing above-average, average, and below-average ability, respectively. Chimera characters have one primary, two secondary, and three tertiary Attribute slots.

Action Rolls

Every action your character attempts has a Difficulty Level (DL) and corresponding Target Number (TN). An action’s difficulty is based on the Attribute used to perform it, as shown on the table below:

Attribute Slot Difficulty Level (DL)
Target Number (TN)
- Automatic 2
- Trivial 4
Primary Easy 8
Secondary Average 12
Tertiary Hard 16
- Strenuous 20
- Impossible 24

Based on the table, actions using your Primary Attribute are Easy (TN 8), actions using your Secondary Attributes are Average (TN 12), and actions using your Tertiary Attributes are Hard (TN 16). When your character performs an action, he must make an Action Roll (AR) with 1d20. If the result is equal to or greater than the required Target Number, the attempt succeeds.

Action Roll Modifiers

Bonuses or penalties to your Action Roll are represented as positive or negative modifiers, which are applied to the Action Roll result. Modifiers represent what the character brings to the attempt: skill, special equipment, or any personal hindrance.

Difficulty Adjustments

Particularly hard or easy actions are represented by a Difficulty Level adjustment, which can increase or decrease an action’s difficulty by a number of steps. For example, an action performed with your Primary Attribute is Easy (TN 8), but if rated at DL +2 (i.e., two steps harder), the action becomes Hard (TN 16). Similarly, if the same action were rated at DL –1, it falls from Easy to Trivial (TN 4).

Action Roll Example

An action’s base TN is always determined by the Attribute used to perform it, but by sliding DL up or down the overall scale, you automatically simulate relative difficulty from character to character.

For a character with strength in his Primary slot, let’s say that bashing down a door is Easy (TN 8). A stuck door would be harder to bash, perhaps represented by DL +1, making the action Average (TN 12). A door bolted from the other side would be truly difficult: perhaps DL +2, making the action Hard (TN 16).

For a character with strength in his Tertiary slot, bashing down a door starts at Hard (TN 16). Using the same adjustments as above, a stuck door at DL +1 becomes Strenuous (TN 20), and bashing down a bolted door is Impossible (TN 24)&emdash;he’ll need at least +4 points of bonus modifiers to do the deed, and even then he’ll need a 20 on the Action Roll.

Special Results

Critical Results: If the AR die results in a “natural” multiple of four (i.e., an unmodified 4, 8, 12, 16, or 20), it’s a Critical Success or Critical Failure. Critical results are better or worse than normal results, and vary according to the action attempted. For example, during combat, a Critical Success might let you to roll an extra damage die, while a Critical Failure probably gives your opponent an advantage. The specifics of critical results are up to the GM.

Automatic Failure: If the action roll results in a natural “1,” the attempt automatically fails, regardless of actual difficulty or modifiers.

Final Words

The Action Roll system is designed to decouple the chance of success from the action itself. This has two immediate advantages. First, it gives attributes a more intuitive and meaningful role, and eliminates the need for attribute modifiers. This latter bit is important: many systems assign static target numbers to an action, with a character’s attribute modifier being applied to the roll. While intuitive, this limits the impact of attributes that have different scores but identical modifiers.

Second, you don’t have to represent difficulty by assigning target numbers to actions. Instead, a character’s attribute slot determines difficulty, which often makes more sense: Strong characters will always have an easier time than weak characters bashing down a door. This approach more accurately represents an action’s difficulty as a function of who’s attempting it. Applying difficulty adjustments maintains your ability to represent particularly hard or easy actions, but the base chance of success always rests on the character’s Attributes.

Finally, the Action Roll mechanic easily dovetails with any RPG’s skill, combat, or “attribute check” systems. All you need to do is connect every action to a character attribute. For example, Tracking skill might be tied to intelligence or perception; use strength for melee combat and dexterity for ranged attacks; saving throws become attribute checks, using constitution for Fortitude, dexterity for Reflexes, and willpower for Will.

While I don’t tout this as revolutionary, I do believe it’s an opportunity to streamline gameplay and put the emphasis of action resolution on the PC instead of the action. I’d be very interested in feedback from those applying this mechanic to their current RPG system.

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  1. anarkeith
    November 4th, 2009 at 14:21 | #1

    Erin,

    I really like this mechanic. Based on 4e, i’ve recently added a three-tiered difficulty system to my homebrewed rules (5/10/15; easy/moderate/hard). I love your concept of tying difficulty determination to the character’s attributes. It seems like a great way to let characters shine at various tasks.

  2. November 4th, 2009 at 17:20 | #2

    Thanks, Keith. This approach has proven to be pretty intuitive in Chimera: there’s never a question about what to roll in any situation, and the GM has an easier time assigning difficulty. Cheers!

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