To begin with, my Yoon-Suin campaign was essentially LOTFP played straight with a few pickings from tenfootpolemic. Inevitably I've houseruled to an absurd degree. I even dropped Wisdom and Constitution because I didn't like how they did basically nothing, but that's a topic for another day.
One thing which bothered me was how Skills were being used in my game or, chiefly, the fact that they weren't.
Just for any non-LOTFP-savvy readers - in Lamentations of the Flame Princess you have a dozen "Skills" representing things like Climbing, Bushcraft, Sneaking and the like. Each had a score out of six. You rolled a d6 when you invoked that skill and if you rolled equal to or under your score you succeeded.
My Specialist (renamed Adventurer) had put points into Architecture and kept using it to find out neat, irrelevant information about buildings. "Oh yeah it's a classic example of French Gothic". Neither of us could really fathom what its true purpose was, even after reading the advice online. As for the rest of the skills - they hardly ever got used. I mean how often do your players climb walls? Perhaps more than mine, to be fair.
I wanted Skills to become a bit less niche and more useful to me in a pinch. I practice an OSR-style philosophy of not hiding information behind perception or knowledge checks - if it made sense that the PC would know/see something, they saw/knew it. But sometimes it wasn't apparent, and in those moments a simple dice throw can be useful.
I found inspiration in an old favourite of mine - Barbarians of Lemuria. Barbarians is a very odd little game - I wouldn't know where to put it on the OSR-to-Storygame spectrum. It's served me well for one-shots and is very easy to run. I highly recommend picking over it if anyone's interested. For what it's worth, the more expensive, newer Mythic version is actually less good than the original.
In BoL character creation is simple - you have four Stats, four Careers, and four Combat Abilities. When you did something you rolled 2d6 and added your relevant Stat (you always added the Stat) and, if it was a combat situation, your relevant Combat Ability too. You beat a modifier and succeeded or failed. However if you were in a non-combat situation then instead of your Ability you would add your Career.
Careers were chosen by the players. Y'see, BoL was trying to represent the wild, wandering résumés of old Pulp Adventure characters like Conan or Fafhrd or Khlit the Cossack. You picked from a list of 20-something examples (e.g. Thief, Slave, Wench, Noble, Priest) and plotted a four-part 'story' of how your character got to where he is. So Conan would be something like "Barbarian - Slave - Gladiator - Thief" or whatever.
So in any non-combat situation you would inevitably have to justify how you could add one of your careers to the roll. So you could add Barbarian whilst out hunting because, of course, that's what you did as a child back in your days on the steppe - or maybe Thief 'cus it represented how good you were at sneaking through the undergrowth after your prey. Perhaps you could add Pirate to a haggling scenario if you argued that there is inevitably some element of mercantilism in fencing stolen plunder. You wouldn't be able to invoke Barbarian in a poetry competition unless you had an exceptionally good reason and a lenient GM.
I created the following replacement for Skills, called Careers:
They function identical to Skills - PCs put one or two points into skills most relevant to their backstory at character creation. Adventurers/Specialists can add to them every level. The mechanic is the same - a d6.
(With my players we inverted the numbers because they kept getting excited when they rolled a 6/6 and disappointed when they remembered that was the worst roll, so I flipped the math and everyone's happy. But you don't have to do that and it's not part of the house rule.)
Each of these careers is invoked when the players perform some task where the skills associated with that career come into play. So if someone wants to tame a wild, bucking bronco they roll Animal Handler. If they want to vanish into the woods for an afternoon and come back with a bunch of skinned rabbits and fresh trout, they roll Hunter. If they want to identify or produce anything herby, potion-y, poison-y they can roll Alchemist.
But isn't Scholar just a roundabout Knowledge Check? I thought you didn't do them
Yes and no. Merely by having any points in a skill - indicating your character isn't a complete fuckwit in that regard - justifies giving out information as per my policy. However Scholar can be used in situations where it's unlikely the characters would really know anything - it gives the smart-alec bookworm types a chance to go "well it just so happens I spent one summer reading everything there is to know about tropical marine botany...". Just like how I don't make players roll Polyglot (1:1 LOTFP's Languages skill) to speak Common, I don't make them roll to know general things. But just like how rolling Polyglot can reveal a PC speaks Hobgoblin for some insane reason which might prompt a bit of improvised backstory-creating, so too can Scholar create a situation where this one character has a funny story for why they know so much about paranumismatics.
What do Arcanist and Medic do?
In addition to providing magical theory and medical knowledge as per Scholar, Arcanist allows practicing wizards/magicians to foreshorten the length of time it takes to research/create spells and Medic allows for non-HP related medical emergencies to be resolved e.g. stemming bleeding, setting a broken ankle.
What about Sherpa?
You could rename that for a less Nepal-centric game (I'm playing Yoon-Suin in the very-much-Himalayan Oligarchies) to something like Scout or Ranger or whatever. It's basically orienteering, mountaineering, local folklore, bushcraft all that stuff.
Doesn't Hunter cover that?
Yes! That's partly the point. Just like in BoL, there are some activities only a one career can do - but there are plenty of activities many careers can do. If you wanted to abseil off a ledge you could probably invoke Sherpa, Burglar, or Assassin (gotta get into top-floor apartments somehow). If you wanted to identify animal tracks, Animal Handler, Sherpa, Hunter, Scholar and maaaaybe even Alchemist if you argue your Alchemist career represents your character spending so much time picking herbs in the forest. Merchant and Thief can both appraise the value of things, Alchemist and Assassin both bond over their love of poisoning people.
By breaking out these skills into various careers but still keeping each career distinct and favourful, players can use the Careers/Skill stat as another way to amplify their backstory and justify so many basic actions. Of course Hunters would know their way around the woods just as well as a Sherpa. But they might be clueless when it comes to travelling over vast distances or fording a river with a wagon of pack-mules. It is not a hard and fast list of what they can and can't do - it's what feels right and can be justified by the PC's life story and aptitude. This is not a rule for min-maxers.
Another bonus to this system is suddenly Specialists/Adventurers start to build these wild and incredibly interesting backstories as they level up. By level 3 my Adventurer has 2 in Burglar, 2 in Engineer, 3 in Merchant, 2 in Polyglot, 2 in Scholar - all of these things hinting at a life-well-lived full of mishaps and adventurers - hence the rename. Just as LOTFP intended, a fighter hits harder, a priest and magic-user cast most powerful spells, and the Specialist-come-Adventurer will smile wistfully and say "this reminds me of that time I spent three months in the jungle with the Bokoko people of Nam-Boo-Lahr. They had a fantastic remedy for snake bites using gunpowder and shoe polish..."