I would like to build my own RPG system. I'm not following any particular trope or format but I do usually enjoy characters who are the sum of their skills. I'd like to actively distinguish skills from each other by grouping them. So far I have established roughly three groups, two of which I believe to be well defined:
- Knowledge skills: The characters understanding of a specific topic, for example they may gain a +3 bonus to diagnosing a disease because they are rank 3 in medicine.
- Item skills: The character has a talent with a specific set of items, for example they may gain a +2 bonus to hit someone with a boomerang because they are rank 2 in boomerangs.
The third section is the one that I'm struggling with, initially I've covered a large range of skills with 'Ability skills', this group current holds everything from strength to dexterity and from will power to lying etc. It's the sort of innate mental, physical and social skills that are more central to an RPG character.
My issue is that I do not feel that things like strength and things like lying really belong in the same area but I can't decide how to break them up. I've considered using physical, mental and social as groups however many of these cross over each other, e.g.: Is charisma/confidence truly a social skill or is it mental? I also find that there becomes an in-balance with many physical skills, a few social skills and practically no mental skills.
What are good ways to group skills? Are there any game formats that display good examples without being too structured?