Musings on the Target Number

Life is like a bag of d20s

I have an occasional tendency to second-guess whether Chimera handles such-and-such as well as I’d like (some of you are already familiar with this irritating habit of mine, by virtue of having seen what amounts to 3 major and 10 minor revisions of Chimera since 2006). Last week, Target Numbers were in the crosshairs, and I thought I’d retrace my thought process for input.

Initial Thoughts

The basis for Chimera Action Rolls is that you toss a d20 every time your character does something meaningful. If the result is equal to or greater than the required Target Number (TN), the attempt succeeds.

20-sided die
My Fav d20

Simple enough, yet this elegance disguises a few “attractive nuisances” for a tinkerer like me.  Chief among which is how you assign difficulty. There are two ways to do this:

  • Adjusting the TN: the higher the TN, the harder the action.
  • Modifying the roll: positive modifiers make the action easier, while negatives make it harder

The pitfall (for me) is whether to use one method or the other, or a combination of both.

Static Target Numbers

I experimented with static TNs (i.e., a roll of X or better always succeeds, no matter what you’re doing). If you go this route, the TN is always the same so you have to reflect difficulty by modifying the actual roll.

Chimera 2.x had a modified version of this: your TN in a given action was based on how you assigned the attribute you were using. Actions performed using your Primary Attribute were TN 8, actions using your Secondary Attribute were TN 12, and actions using your Tertiary Attribute were TN 16.

This had the nice benefit of giving different characters different TNs for the same action. Success was always based on what the character brought to the table—a PC with Strength as his Primary could bash down a door with TN 8, while another PC with Strength as his Secondary would bash the same door at TN 12.

It also made it easy to determine the required TN for a given roll. No subjective dithering about whether an action was “Hard” or “Very Hard.” Oh, you’re trying to find a clue and Intelligence is a Tertiary Attribute? Roll 16 or better.

Now, despite what I wrote a few paragraphs ago, the GM could still adjust the TN to reflect difficulty, but such adjustments were done in increments of TN +/-4. And that could get onerous, especially when skill improvements were applied in increments of +/-1. Good on paper, but not always fun for the players.

Action Roll Modifiers

Chimera 3.0 (aka Chimera Basic) got rid of this convention wholesale by ditching attributes and moving entirely to Abilities. In this model, class-based Abilities start at TN 16, and each improvement reduces that by 1 (i.e., a class-based Ability that you’ve improved 3 times is TN 13).

It’s simple, but not intuitive. First, where did 16 come from? Second, doesn’t it make more sense for an improvement to be “+1” instead of “-1”?

Well, the first bit hails from my B/X days, when I revamped action resolution in my Classic D&D game. Unfortunately, a D&D 16 is easier to attain than a Chimera 16, so that didn’t quite work as well as expected. The second bit—using “-1” instead of “+1”—is just pure idiocy on my part. Of course “plus” means better than “minus.”

Another aspect of this approach was that I started tweaking Action Rolls from both sides, meaning the Chimera Basic rules are rife with situations where you adjust the TN, but there are also plenty of times when you adjust the actual d20 roll.

In practical terms this means that an adjustment of TN +2 (i.e., making the required TN 2 points harder to achieve) is the same as AR -2 (i.e., subtracting 2 points of the roll result). In other words, if I’m up against TN 16, an adjustment of TN +2 or an AR -2 both actually mean that I need to roll an 18.

I find this partially confusing, because it erodes the consistency of assigning difficulty to an action. Do you tweak the TN or the AR modifier? Does a low-visibility penalty reflect the action’s inherent difficulty or just how poorly your character deals with dim light?

And, while this system allowed you to easily record each action’s TN (e.g., “Wield/14” leaves very little room for ambiguity), the benefit is offset by the potential inconsistency with which the action’s difficulty is affected by external factors.

Logical Blend

My OCD leads me to the following approach:

  • The GM assigns Target Numbers based on an action’s inherent difficulty (see below)
  • The PC modifies his Action Roll based on external factors (skill, environmental conditions, special gear, magic, etc.)
  • Abilities are recorded with their AR modifier (e.g., “Wield +2”)
  • Resistance rolls and other actions are recorded with their actual TN (not a TN or AR modifier)

Based on difficulty, the Target Number scale looks something like this:

  • Automatic: TN 2
  • Very Easy: TN 4
  • Easy: TN 8
  • Average: TN 12
  • Hard: TN 16
  • Very Hard: TN 20
  • Impossible: TN 24

Similar to what Chimera 2.x presented (and reinforced by Deimos, whose wisdom is great).

But what about smackin’ the beasties? I think the TN is based on the target’s size. I’ve wrestled with Size-based “to-hit” modifiers before, but couldn’t make them work without extra bookkeeping. But this may be the “right” way to introduce this aspect of fighting. What about:

  • Target is smaller than attacker: TN 16
  • Target is same size as attacker: TN 12
  • Target is larger than attacker: TN 8

The only “hitch” to this system is that I think it’s pretty much what d20 or D&D 3.x already uses. That’s not necessarily bad (meaning, if it’s more familiar to players, then it eases Chimera’s learning curve), but I’m not versed enough in 3.x to know where the disadvantages lie.

Final Words

OK, the skeptical amongst you will count this as minor revision #11. But (and I stress this), the approach above doesn’t alter how Chimera Basic is played—it merely changes how the Action Roll/Target Number rules are presented. You can use your characters and stat blocks as they exist now—just subtract current Ability TNs from 16 to figure the Action Roll modifier (e.g., Fight/15 = Fight +1).

That said, I plan to roll this around for a few days and actually write it out. If it passes muster (and pending your feedback), this will make it into the 5th (and I think final) printing of Chimera Basic.


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