Writing your own game can be the work of years.
Mine has been an on and off process for decades and alwaysbstems from the same basic though; “I do not totally agree with the characteristics used by most games”.
My first two RPG ‘awrenesses” were the first editions of that ancient D20 game and Traveller. They had very different takes on characteristics, both with merit, but also both with issues for me.
Strength, Dexterity, Constitution, Intelligence, Wisdom and Charisma
vs
Strength, Dexterity, Endurance, Intelligence, Education and Social Standing
Three are agreed upon, one is re-worded, two are very different. The game themes are also very different though and within their own envelopes, pretty much ideal (although I have never settled with Soc). The reality is, you could get away with the Tri-stat like Body-Mind-Spirit/Soul and make these a base for more specific skills and abilities, but that for many is too vague.
My next and most enduring game paradigm came from D100 games who use a slightly different and often flexible set;
Strength, Dexterity, Constitution, Intelligence, Size, Power, Charisma, Appearance or Education. The itialicised ones come and go, generally, but not always settling on just Size and Charisma.
Pow is the odd one for me. It is sometimes ideal (supers, fantasy, horror), sometimes just an odd one.
At first I tried to break it down to six defining, core chrs;
Prowess (Strength and Agility), Dexterity (fine motor skills), Reason (left brain), Intuition (right brain), Resilience (physical and mental) and Presence (the force of ones {“self”).
My main issue, that even with these six to me, perfectly balanced representation of a person or other being in a role playing environment*, there is little room to combine them into a 2x chr + skill vs d100 mechanic. They are too comprehensive and inherently over lapping, leaving little room for discreet definition. Goos for a different system, but not my needs.
I decided to go back to a more deterministic set of eight characteristics, allowing for more defined and flexible wording.
These are broken down into four sets of two (a rigid and flexible characteristic to each pair), each directly connected but effectively opposed;
Physicality.
Strength and Dexterity, (the physical realities of your body, that can be honed and even changed, but are generally a part of you from early on).
Physical Condition.
Endurance and Agility. These are more down to your age, activity level and general up keep.
Intellect.
Reason and Intution. The left/right brain, logic vs creativity pairing. Intact from the above six, these two have become entrenched in my thinking.
Personality.
Will and Presence. These two are a measure of inward and outward projection of personal strength or character. Like the others, the player character can excell at one, usually at the expense of the other, with rare individuals solid in both**.
By splitting Resilience and Prowess from above, I can now re-constitute them along with several other primary combinations as the building blocks for my d100 mechanic. The mechanic assumes 2x characteristics as the base with a skill level and experience value applied for a total vs a d100 roll in a roll under is better format.
This is not a one-off, fixed combination, but rather a “by circumstance” design, so gun skill may be applied to a quick draw (Reflexes), autofire (Prowess) steady aim (Balance) or knowledge of a weapon (Perception or Concentration) test. This allows the skill list to be reasonably broad, but realistically and individually applied, in other words, skills and chr tests are intertwined, but not exclusively connected and fully flexible.
From here we can generate combinations that are more or most common, so they will be worked out on the PC’s sheet as a helpful guide and to reduce wording later.
Combining them each with themselves gives us the pure chrs;
Physical Might, fine motor skill Manipulation, physical Stamina, physical Flexibility, intellectual Wisdom, inherent Luck, self Discipline and overall Charisma.
Combining the pairs of matched/opposed chrs defines the parent group;
Physical Focus, Physical Condition or Health, Intelligence or Perception and Character or Spirit.
Combining logical pairings within the same physical and non-physical groups.
Str + End = Consitution, Str + Agl = Prowess, Agl + Dex = Coordination.
Rsn + Wil = Concentration/Retention, Rsn + Pre = Persuasion, Pre + Int = Empathy.
Mixing the physical and non-physical groupings allows us to define another half dozen common pairings;
Str + Wil = Physical Tenacity, Int + Dex = Reflexes, Pre + Dex = Poise, Rsn + End = Determination, Wil + End = Resilience, Int + Agl = Balance.
These can also help define the core principals of the characteristics in players minds.
It is possible from here to define quite detailed character traits;
A charming, even glamourous character, devoid of empathy and clumsy both socially and physiclly could be high in Presence, Agility and Endurance, but lacking Dexterity, Intuition, Reason and Will.
A street wise tough, lacking in social graces from a 30’s Noir novel may display high levels of Will, Endurance, Intuition and Strength, but be low in Presence, Reason and Dexterity.
For NPC’s it may be as simple as generating the secondary stats only (2 graded averages take from a master list), so you know how well they shoot, fight or interact in their chosen forms. Of course the GM may simply assign skill values that make sense.
In theory, any two chrs may be combined, such as Wil + Dex for handling fine tools in a delicate, dangerous operation (a Starfleet doctor disarming a torpedo on the surface of a moon) or Agl + Pre for pulling off an alluring walk (any Bond femme fatale), but for the sake of expediency, the above work just fine as a base for most skill tests. The GM and players may work together to “work” the system, using good story telling to sell any concept within reason.
*
The skill system is a simple 1-4x level*** and +1 per year of experience as a % multiple of the base chr combo, so the skill is expressed as skill level (1-4, but 1 may also be only “aware”) + experience in years.
The “average” for a master of a skill is 84% (4x21), with rare cases of 100% can be reached (maximum), but only in some combinations. This gives a skill several ways of being applied, nuancing the system closer to reality.
Take a character dynamic like “The Good Doctor” as an example. A high level logic and analitical mind with poor to nearly non existant empathy can be effective in a team, even with a relatively low level of experience, but the other doctors, even if less skilled but more experienced or more skilled but less intelligent add the other dimensions needed to balance the team out.
Skill tetsts are applied using a pool of d10 die, assigned by difficulty (we use red and blue die);
Mundane. 3d10 (blue) take the best combination of 2. A test only rally used if failure can lead to consequences or drive the story.
Standard. 2d10 (blue) arranged as wanted. The base test assuming no direct opposition or pressures are applied.
Challenging. 2d10 (red/blue) arranged in pre determined order (red 10’s, blue 1’s). This is the base for most opposed tests without advantage.
Difficult. 2d10 (red) in worst possible order (Crit-any, highest fail, lowest pass). Pushing hard or without advantage.
Daunting. 3d10 (red) using worst two.
Improbable. 4d10 (red) using worst combination of two.
etc.
Familiarity without training usually adds 1 level of difficulty, sometimes more and occassionally no skill check is allowed (a recently discovered New Guinea tribesman trying to land a Jumbo jet).
Doubles are critical successes or failures,
an optional table of consequences can be used (low crit succusses and high crit failures are less dynamic than the opposite),
higher success or lower fail rolls are better if opposed,
“00” always fails and fumbles if not 100% chance.
*It can cover animals (highly intuitive, lower reasoning), automitons (the reverse), avoids blow-outs, like super strong types, by concentrating more on the coordination of physical characteristics and leaves plenty of room for interpretation (the difference between Darth Vaders and a super models Presence for example can be defined by other chrs).
**Chrs are usually generated by rolling a pool of 6d6 and assigning three to each chr. The player can then aim for a balanced share, or extremes. In some systems, the pool may be increased or decreased, the assigned split changed or limitations loosened.
***Familiar (as a base only with extra difficulty applied), trained, proficient, expert, master.