Monday, June 23, 2008

3d6: IMARS

Looking at the prevalent ability score ranges from those 16 possible results of 3-18, and knowing the odds of the bell curve, we can take the standard OD&D Prime Requisite modifier bonus and see if there is a better method to determine those levels, regardless of the actual scores.

In Prime Requisite terms, there are five levels of modifiers, which I have dubbed superior, above average, average, below average and inferior. If one is considering using such ability range descriptions, I’d reword the cumbersome Above Average to Respectable, and Below Average to Mediocre. Here are the scores grouped by the odds of actually rolling them:

Superior (15-18): 9.3 %
Respectable(13-14): 16.6 %
Average (9-12): 48.2 %
Mediocre (7-8): 16.6%
Inferior (3-6): 9.3 %
Why in the world would I even consider dispensing with my beloved 3d6 bell curve? Simply to show how the numbers are, for the most part, relative to one another and not as important as the modifier that is attached to them. Per the OD&D rules, this five level range of modifiers applies to all but one of the six abilities, CHA. Charisma deserves it’s own post; it’s the most complex, in depth ability, and provides modifiers for Reaction, Henchmen and Loyalty, with seven levels of modifiers (and the only ability were 18 actually means something in game terms). Now, not all five abilities differentiate between Superior and Respectable, or Inferior and Mediocre, but the important break points are there. Specifically, for the three Prime Requisites of STR-INT-WIS, these five levels determine whether the character receives a modifier of any kind to his or her experience gain.

So, in looking only at the percent chance of ending up with the various modifier ranges, we can tackle a method to provide nothing more than the descriptive value for each ability, instead of a numerical value.

If we are willing to round these percent chances somewhat generously, we could convert this system to a simple linear d20 or perhaps a more exacting percentile roll. I’m big on easy to remember numbers, so I’d lean toward a d20 roll myself, something like this:

The IMARS d20 Roll:
1-2 (10%) Inferior
3-5 (15%) Mediocre
6-15 (50%) Average
16-18 (15%) Respectable
19-20 (10%) Superior
If one were to use the IMARS ability method, one would truly be using a more abstract treatment of the D&D ability scores. Simplifying them in such a manner would likewise force a facile system for other non Prime Requisite modifiers and ability checks.

I’m of the opinion that the STR-INT-WIS abilities are perfectly fine doing nothing more than influencing experience. Perhaps some bonus for Superior STR, such as +1 to Open Doors (which I use in my own campaign) would be in order. Per the OD&D rules, we can readily convert IMARS to what those ranges mean, like so:

STR-INT-WIS(No modifier at all unless the below category is the character’s Prime Requisite).
I - Minus 20% from earned experience.
M - Minus 10% from earned experience.
A - No modifier.
R - Add 5% to earned experience.
S - Add 10% to earned experience.

CON (In OD&D, each CON point has a 10% ‘survival’ chance tied to it, but doesn’t explain what surviving adversity truly entails. For IMARS I’ll convert the chances to relative percentages.)
I - Minus 1 from each Hit Die, 25% Survival Rate.
M - 50% Survival Rate.
A - 75% Survival Rate.
R - 100% Survival Rate.
S - Add +1 to each Hit Die, 100% Survival Rate.

DEX (In my campaign, I’d add that S receives a +1 bonus to Sneak attempts and Armor Class).
I, M - Fire any missile at -1 to hit.
A - No modifier.
R,S - Fire any missile at +1 to hit.

CHA (I’ll have to dumb down the OD&D system to make it fit IMARS, I basically threw out the CHA 18 numbers).
I - Max Hirelings: 2, Loyalty Base: -2, Reaction: -1.
M - Max Hirelings: 3, Loyalty Base: -1, Reaction: 0.
A - Max Hirelings: 4, Loyalty Base: 0, Reaction: 0.
R - Max Hirelings: 5, Loyalty Base: +1, Reaction: +1.
S - Max Hirelings: 6, Loyalty Base: +2, Reaction: +1.
Of course IMARS can still be rolled using the simple elegance of the 3d6 bell curve, and I would probably do so if I ever instituted IMARS into my D&D games. I like the system because it deemphasizes the actual numbers that we so often get caught up in while creating characters; on the other hand, it takes away from the abstract descriptive nuances of actually using the numerical values. As I’ve mentioned before, I love those little numbers as they often actually breathe life into the simple collection of six ability scores.

Nevertheless, even if you retain the numeric values, the five ability ranges could still be used in order to simplify the ability score modifiers for your games. In the end, I’d use the 3d6 method, retain the numeric values, but understand and apply the level modifiers as shown above. An IMARS/traditional hybrid, if you will.

~Sham, Quixotic Referee

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