In terms of narrative, every stat is being used to superhuman levels.
Thanks for adding some additional things for me to contemplate! But regarding this portion of your response, I this that is only true if the developer makes it so.
I am an ancient school player who cut his teeth on 2E D&D and the very first CRPGs. As I recall, and my memory might be playing tricks on me because I am old, those games didn't cater to the superhuman feats, powers, actions, etc. like most modern games do now. You didn't have powers where the fighter somehow manages to hit every single enemy on the battlefield or a monk that can jump across a chasm. Personally, I dislike games where the main character (MC) runs around with a weapon as big as them and they wield it around like a toothpick. And I don't like games where the MC can spin around in circles like a top, hitting everything around them. But that is just me.
The most powerful, mystical, non-human aspect of earlier games was the magic system, at least from my experience. And even the magic wasn't super over the top. Not until you reached the highest spell levels. Those early games didn't have Tiers, and Paragons, and Powers, etc.
From my perspective, a stat system that has 18 has its naturally highest value is where an 18 represents someone who is reaching the best of what the human body and mind can achieve, on average. The average adult would have around an 8-12 stat. A 19 or 20 is pushing into the your in the top 1% of the world. And above that is deity level.
For me, I don't plan on making skills, powers, whatever they are called that are "superhuman." I want to try to keep all of those things within the realm of what is possible. And higher skills would be reflective of mastering your class/profession. Now, that might not be fun for a lot of players, but I am approaching this as a hobby. A love letter to myself for the type of game that I want to play.
As far as mechanics, I think step one is going to be finalizing what I think I want for my core stats. Then, as I build my character classes, I think my step two will be to determine if certain classes will have minimal thresholds for certain stats. Then, generally, I think I will try to design a system of stat bonuses where any class would benefit from them in appropriate ways.
Older systems were already designed that way, it was just rare, in my experience, for players to try to get higher stats for things that didn't directly benefit their primary class. Which often led to very stereotypical character builds. Like weak bodied magic users with superior intellect. Not always, but fairly often. Or very strong and agile fighters who weren't the sharpest knives in the drawer.
And if I do have a stat like Wisdom, and if it seems like that stat should be able to "grow" beyond the natural cap of the other stats, then I would want to make any increasing bonus associated with that growth to benefit every class is an appropriate way. But, there are arguments that the entire concept of Wisdom could be removed because it is replaced by something else.
For instance, take a game that incorporates skills for most everything. Traditional skills, physical skills, mental skills, weapons, armor, etc. Each of those skills has a numeric value from 0 - 100. With 0 being you have absolutely NO skill & knowledge in that area. You don't know the first thing about it. If you pick up a weapon with 0 skill you are more likely to hurt yourself than someone else. Or if you try to swim with a 0 skill you are most likely going to sink and drown. And 100 being that you have reached mastery level, which would be rare for most inhabitants of the world. And everything is based around those "skills." How likely you are to hit something with a weapon, how many attacks you might get with that weapon, bonuses to damage, how effective your armor is, how long your stamina lasts, how effective you are at picking locks, how effective you can perform any action, whatever.
Some people might argue that those "skills" replace a Wisdom stat. And I sort of like renaming the traditional Wisdom stat for use by cleric/priest/mental types with something like Piety (more deity linked) or even Willpower (which is actually a much more broad term). Willpower starts to go down the road of Wisdom a bit. Any person, regardless of their class or specialty, can potentially improve and benefit from Willpower. At least the way I think of Willpower. And maybe Willpower is another concept that doesn't have a natural limit, like some other stats seem like they might.
Regardless, everyone here has given me a lot to think about so thanks for all these thoughts and perspectives! I am just going to try to make sure that whatever I implement is as balanced as it can be and hopefully, mostly behind the scenes so the player doesn't have to get caught up in thinking too much about it.
