I'd like to return to a a couple ideas up-thread that I would like to see incorporated into skills:
I definitely prefer adjudication:
- Player describes attempted action in character
- DM decides mechanic to use
Ie, using Str or Dex or Con for Climb, depending on the situation. Although I would like to add that the player can "present a case" if they feel the situation warrants it. As always, DM adjudication, and a player constantly using Cha for their Climb check should not be mollified.
I think, after considering the various arguments, that I prefer a hybrid.
There should be a short, set list of adventuring skills for the most common rolls to which training matters. This is for speed of play and fairness.
In addition, characters should get a bonus whenever their background applies to a situation that isn't covered by the set skill list.
This. And here's a thought for designing it...
I like the "siloing" of Next, and there was a discussion for separating out "combat feats" from "roleplay feat" (maybe calling them "traits").
Assuming that Backgrounds have some sort of level-up progression, why not do this with skills, too?
Create a short list of "combat skills," skills that come up all the time in adventuring that PCs have felt the need to invest in to keep up. Things like Perception, Thievery, Bluff, even Climb and Jump. Your class might give you automatic training in one or more of these, and you can spend the combat feat Skill Training to get a +3, and the combat feat Skill Focus to get an additional +2. Each skill has a primary attribute (Wis for Perception, Str for Climb), but the DM is given advice to use different abilities depending on the situation.
These skills can obviously be used outside of combat, but they are "adventuring skills," skills that every adventurer, at some point, might find themselves doing or wanting to invest in.
This can even open up the design space. "Initiative" becomes a combat skill, for instance.
On the pillar side, you have Background with Traits and RP Skills. RP Skills are more general and more situational, providing you with a +3 bonus to those situations that align with your background. At later levels you can gain additional skills or additional Backgrounds that expand your capabilities in the RP department. Some might even stack with your combat skills, if the situation warrants it.
Let's say you're a Fighter with the Pirate Background.
You choose two skills from a class list to gain Training (Let's say... Athletics and Perception). For your 1st-level feat you choose to gain Training in a third skill (Let's say... Thievery).
Your Pirate Background provides you with a ship and crew that you belong to, and whenever you are in a port town you can make contact with them for information and resources. Instead of a list of skills, maybe just a +3 bonus to all "pirate-y" situations? Perhaps every five levels you gain a second Background?
Now let's say your character is fighting at the docks and falls in the water and tries to swim in the rough water. +3 bonus from Athletics, but another +3 for being a pirate: +6 in this particular situation. Or your character tries to find out who the local pirate king is. Just +3 bonus from being a pirate.
So, pretty much what
Jeff Carlsen said. A short list of adventuring skills that you train with your combat pillar (through classes and feats) that includes things like Perception, Find Traps, and even Initiative. And whenever a background applies to a particular situation, stack on that bonus.
As a module, you could develop a fully fleshed out skill list that includes Diplomacy, Use Rope, Appraisal, and Lore. Tack this module onto Backgrounds, and now your Background provides you with an rp skill list along with your combat skill list.