From: cctr120@cantua.canterbury.ac.nz (Brendon Wyber)
Subject: RPG: Making your own role playing system
Organization: University of Canterbury, Christchurch, New Zealand.
X-Newsreader: TIN [version 1.1 PL8]
Date: Thu, 28 Jan 1993 05:26:38 GMT




           SO YOU WANT TO DESIGN YOUR OWN ROLE PLAYING SYSTEM ???

Role playing systems seem to be getting more and more similar in design.
Using the following notes as templates we can easily create the 
basis of your own role playing game. NOTE: this article concerns
the Mechanics not the background of the game and focuses on the character
definitions, which is usually the most important aspect of the game.


STEP ONE: THE BASIC SUCCESS CHECK

The first thing you need to decide is the basic rule mechanic on how a
character will succeed in a doing success checks for skills/characteristics
etc. This is the most important part of the game as it will effect all the
numbers to follow in the game. It usually involves rolling dice and comparing
the result to a score on the character sheet.

e.g. GURPS/HERO: Roll 3d6. Result should be less than or equal to the score.
     Runequest/Warhammer RPG: Roll 1d100. Result should be less to or equal
                              to the score.
     Rolemaster: Roll 1d100, add score. Look up on a table, etc.
     ShadowRun: Roll a d6 for each point in the score. Count the number of
                dice that get higher than a certain number.

More advanced games have rules for flukes (often referred to as fumbles,
botches, criticals, specials) or rules involving extra dice rolls to get
numbers beyond the range normally available.

e.g. Harn: Roll a 1d100. If the roll is a multiple of 5 the result is a
           critical instead.
     Ars Magica: Roll a 1d10. If the roll was a 1, roll again and double it.

Things to remember...
 1)   The larger the dice the more maths involved. People often
      prefer rolling a 1D20 to a 1D100.
 2)   Having rules for flukes, or getting higher than normal dice roll remove
      the concept of "never being able success or fail" syndrome. Including
      them can, however, create the "only fail when I fumble" problem.
 3)   Rolling one dice (1d20 or 1D100) is a linear probability curve while
      rolling more is a bell curve probability. This effects the modifiers
      to a score. On a 1d20 a +2 modifier will add +10% to the chance of
      success regardless of the character's original score, but a +2 bonus on
      a 3D6 roll will have a bigger effect on a score of 9 than a score of 13.


STEP TWO: CHOOSE THE CHARACTERISTICS

Every game since D&D and traveller has had the common concept of the 
characteristics, a bunch of primal values that builds a frame work to
help character design. There seems to be two common ways of doing this.
First is that all the characteristics are equal and independent of each
other.

e.g. D&D: Strength, Intelligence, Wisdom, Dexterity, Constitution, Charisma,
          all generated from 3D6 rolls ( yeah right :-> )
     Ars Magica: Strength, Stamina, Dexterity, Quickness, Perception,
                 Intelligence, Presence, Communication, all allocated from
                 points or rolled randomly.
     Traveller: Strength, Constitution, Dexterity, Intelligence, Education,
                Social Standing, all 2D6 rolls.
     etc..

The other method is two have two sets of characteristics. One primary and
one secondary which is calculated from the primary's and other modifiers.

e.g. 2300 AD: One of the physical characteristics is Mass, which is then
              used in the calculation of strength.


Once the actual characteristics are chosen then then standard range of values
are decided on.

e.g. GURPS, D&D, Hero: Have an average of a round 10, common mortal man
                       is in the 3-18 range.
     Ars Magica: 0 average, normal range -5 to +5.

This number is usually easily applicable to the Success Check Method in order
to do simple characteristic roll. Bear in mind for some reason player
characters score are usually higher that average.

e.g. Runequest: Uses the 1D100 system. Characteristics range from 3-18. A
                normal roll involved rolling less than the characteristic 
                score times 5.

Note: the more characteristics chosen, the more complicated the maths will
be (as they will involve more modifiers). If you have more than eight
characteristics, you will generally have a more complicated game than average.


STEP THREE: GENERATE COMBAT STATISTICS

The combat statistics are then generated from the characteristics. These
involve things like the hit points (for absorbing damage), carrying
capacity, and movement rates.

e.g. Runequest: Things like strike ranks, Hit points, Fatigue points.
     Hero: Endurance, stun, physical and energy defenses, speed, etc.

Some systems then later allow character's to modify those values through
skills, advantages, or by "learning them".

To do this also involves the defining of the combat sequence and timing. The
most common way to do this is to have a "melee round" type system and some
sort of initiative order.

e.g. Runequest: Has strike ranks. You act on the rank.
     Hero: Has speed. Speed determines which phases of the round you act
           in. You then act in order of dexterity.


STEP FOUR: GENERATE ADVANTAGES, DISADVANTAGES, AND SKILL LISTS.

Advantages are things that give bonuses to the characters.
e.g. Ambidexterity, or photographic memory. 

Disadvantages are similar but hinder rather than help the character.
e.g. No legs, or fear of something, or hunted by someone.

Some games don't bother with these but they are becoming more popular in the
more advanced games (Hero, GURPS, Ars Magica, Top Secret) as they allow the
game to define rulewise something that isn't easily measurable numerically
(unlike a skill score).

Skills are measured abilities used to fight with various weapons, drive
various vehicles, pick locks, know things, etc, etc. Ever since the
concept of "All character's of the same Class know how to do the same
thing as well as their level" died away, most games allow character's to
learn abilities separately, each having their own score.

Basically just write down every advantage, disadvantage, and skill you can
think of. Then go through your list and cross out the ones that are
inappropriate, and you have your lists.

Defining the skills isn't that important at this stage. What is more important
is making sure that the value they are measured by is relevant to whatever
method of Success Checking you decided on. Also most games have away that the
score of the skill is modified by the appropriate characteristics.

e.g. Hero: The score is based off the Characteristic (usually 10) divided
           by 5 and add 9.
     Runequest: For every point of Intelligence over 10 the character gets a
                +1% to every knowledge skill.
     GURPS: A score in a skill is based directly of the attribute score
            modified by a constant.

Also determine how many skills are character is expected to have, and what
a normal professional level is in that score is, failing to do this now may
cause problems later on.

e.g. Rolemaster: In the original core rules, the character had an average of
                 about 40 points in which to buy scores in skills. A starting
                 fighter-like character would be expected to buy about 10
                 skills. Later on in companion 2, a lot of existing skills
                 were split into several sub-skills, and a lot of new skills
                 were added. As a result that 40 points now had to be spent
                 amongst a larger number of skill. This caused problems
                 resulting in weaker or more tightly specialized characters.


STEP FIVE: DEFINE THE EXOTICS

According to the background, exotic features must be added. For fantasy games
it spells, for space it is usually psionic (psychic) or alien powers,
etc, etc. This is much too specific to get into here.


STEP SIX: NOW DO THE WORK

This is the most difficultand time consuming of the steps. Here you start
writing things down and are forced to go into details about things.
Consequently this is where most people stop.


SUMMARY

Thanks for reading this. I would be interested in hearing about games that do
not fit this mold, where when looking at the character sheet you do not see
sections labels Characteristics, Disadvantages/Advantages, skills, special
powers, and a section for all the combat statistics.

Be seeing you,

Brendon Wyber                     Computer Services Centre,
b.wyber@csc.canterbury.ac.nz      University of Canterbury, New Zealand.

"Ph-nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn."

Newsgroups: rec.games.design