Simplifying attribute derivatives in my house rules, here are some intermediary notes to self.
I am using a system where an attribute score is likened to an Armour Class. If you have a STR of 16, an opponent challenging your strength has basically to roll 1d20 ≥ 16.
As seen in Ability and Roll High, when challenging yourself, you use the TC instead of the DC, where TC = 21 - DC. So if you exert yourself, the referee might require you roll 1d20 ≥ (21 - 16).
I liked the concept of the Physical / Evasion / Mental saves in Stars Without Number & al, so I took it but made them averages between two attribute scores instead of best of the two attribute modifiers.
Instead of six attribute scores, there are now nine attribute scores. I [naively] see it as a) granting the referee more granularity when adjudicating a roll Difficulty Class, and b) bringing back in some attribute scores, ensuring they don't become dump scores.
In the current iteration of my house rules, I went a bit too far and added Body and Soul averages. They take as input three attribute scores (guess which). It's a bit unwieldy. Averages of two scores are easier to compute without a calculator. And I'd like the character creation to be fast, especially that mechanical part.
I'm dumping Body and Soul but keeping IMPulse and Learning.
IMP (impulse) is the average of DEX and WIS, and it's used in initiative, currently you roll 1d20 + IMP to determine initiative rank, but I'd like to turn it into a check 1d20 ≥ IMP, to part between those who are in and those who are out.
Impulse stands between quickness of hand and awereness, hence my using it in the initiative field.
LEA (learning) is used when upgrading, acquiring new skills. It's used as a check, to determine if your knowledge acquisition is fruitful or not.
The graph is a bit unbalacend, with WIS sitting in the middle, and STR and CON isolated like a british island.
I reconnect the STR CON island thanks to FORtitude and COOrdination. Is there a need to reconnect or is that my wish for symmetry? It's still quite unbalanced, but if you look at the last image in this post, you'll see my original note about it and it forms some kind of E or Σ.
Still that leaves CON and CHA as "leaf" stats.
There is the temptation to connect INT and CHA, maybe labelling it PERsuasion, where have I already seen that?
What would I call the average of CON and of WIS? Some kind of quiet strength?
I need to rearrange the character sheet along that Σ sigma pattern.
This rabbit chase is probably going too far, but at least this post is witness to it. It could also give ideas to other house rule developpers.
I am trying to stick with the six attributes and to make them matter somehow. The modifiers are nice but they feel like a dissolution. Directly using attribute scores or averages of attribute scores as DC feels right to me.
The players anchored their luck in the attribute rolls at the beginning of character creation. It has to matter.