Neat.
In my games this is the list of skills:
Str: Athletic, Intimidation, Ride
Athletics: awesome.
Intimidation: I can live with this.
Ride: I view ride as two things, Persuasion and Athletics. In my experience of horse riding, one absolutely must have an emotional rapport with the horse. As long as the relationship with the horse is good, any stunts or stumbles are basically an Athletic balance check.
Con: Concentration, Survival
- Con mod is used for saving throws and Healing rate (added to each instance of healing received). Con score determine the starting HP of a character at level 0 hp (at 1st level and each following level, you add 1 roll of your HD, without the Con mod).
Concentration: I have mixed feelings about the official Concentration mechanic. I like how one powerful spell at a time is important to really balance Wizard and Fighter. But I hate how a class feature like spellcasting can be disrupted. If Concentration is to need a saving throw (or a skill), I prefer the caster uses the spellcasting ability of the class. Wizard uses Intelligence to maintain concentration, Bard uses Charisma, and so on. If a skill is available to improve concentration, I would rather have Arcana be the skill to know how to maintain concentration.
... Arcana: Now that I think of it, Arcana should probably be the spellcasting ability, whichever this is.
Survival: The official Survival includes things like navigating a ship, knowing which foods are poisonous and which arent, how to recognize and pursue animal tracks, and so on. I am unsure how relevant Constitution is for it. I even feel Wisdom is inappropriate, and it should be Intelligence, which is why I fold it into Nature.
Dex: Deft hands (thieves' tools, calligraphy, precision crafting), stealth
Deft Hands: awesome. It is the proper definition of "dexterity". It also becomes relevant in magical rituals and alchemical formulas that require precision.
Int: Search (investigation, spot), Riddle (bluff/disguise/puzzle/cryptography, ciphers etc), Culture X (act as language proficiency and etiquette/lore about a specific culture)
Search: I like the name Investigation and feel it also includes intuition. So Intelligence handles knowledge generally, including intuitive ways of discerning knowledge. I feel spot like Perception, should depend on a specific skill, like using Stealth to spot someone hiding.
Riddle: Not sure what to do with things that are more like "DM gives a hint". Cryptography and deciphering an unknown language, I get it, but am unsure what to do with it. I would probably use Investigation as a catch-all.
... Things like art, esthetics, disguise, acting, and so on, all somehow relate to Performance, and could potentially make Performance a valuable skill, but I am unsure how to go about it. Some things seem to need two checks. Dancing might use Athletics for the technical skill and at the same time use Performance for how esthetically pleasing it is to the audience. A realistic painting might use Deception for the illusionism and Performance for its beauty and financial worth. Similarly, disguise might use Deception for technical visual simulation and Performance for the skillful portrayal. I havent fully thought these kinds of artistic abilities.
Culture X: Actually, including knowledgeability about a culture with the ability to speak its language, is completely accurate! Great idea.
Wis: Religion Lore, Nature Lore, Arcana Lore
- Lores were moved to wisdom in order to mix the knowledge of those things AND their wise, concrete application in the real world, making them more about practical knowledges than theoretical ones (which would be intelligence).
Religion: For me, religion is two things: History for same-plane cultures, or Arcana for other-plane cultures, depending on the question. But now with your Culture X in mind, I want to rethink how this should work.
Nature Lore: For me, strictly Intelligence.
Arcana Lore: Now I think, this should be whatever the casting ability is, whether Intelligence, Wisdom, or Charisma, and default to Intelligence if the caster is unknown.
Cha: Empathy (Insight, Persuasion), Performance (arts/music instruments), Animal handling, Gamble
Being proficient with a tools gives you advantage when making a skill check using that specific tool.
Empathy: Awesome.
Performance: See above with disguise and riddle. Could be a valuable skill.
Animal Handling: As mentioned earlier, I make Animal Handling part of Persuasion, and here part of Empathy. So much of rapporting with humans, including children, is simple, basic (namely animalistic) needs, like comfort and safety. It can be that Animal Handling is more like a Tool proficiency, in the sense of a Vehicle. It would include all the necessary information and skills relevant to the animal, including Ride.
Gamble: I would fold this into Performance, while I am still rethinking Performance.
Tools: I love 5e Tool proficiencies. I am still getting a feel for them, since Xanathars. I view them as specialized skills that are nevertheless quite useful in their own right. Tools are the best magic item crafting mechanic ever! Let Alchemist make whatever item makes sense for alchemy, and Blacksmith for magical sword and armor. The DM can still gatekeep which items are allowed by requiring more difficulty and special ingredients and circumstances. Advantage for skill-tool overlap seems fair, general knowledgeable and special knowledge can both help.