CapnZapp
Legend
There are several cool things about S&S and also too much dogmatic discussion ("you're having badwrongfun"). People take the right to judge others as if they can't separate fiction from reality. Just because I want inequality in my S&S does not mean I condone it or want it in real life. Duh.
I'm sorry but your three core traits boil down to playing a murder hobo and that doesn't set S&S apart.
I would instead say the core element is that the stories aren't epic. I would not say S&S is low fantasy, but at least it isn't high fantasy and certainly not epic fantasy. Threats and possibilities are more grounded more human. If you can just jump over castle walls, or teleport through them, or level mountains with a stare it isn't S&S. On the other hand, S&S has no time for pig-farming low fantasy either.
So most low-level fantasy fare would work from a story progression perspective. The trappings are of course different. Actually you need a different world than your regular D&D feudal villages to help players recalibrate their expectations and their roleplay. If you act like a true S&S barbarian in the small town of Somerset everybody is going to be upset or disgusted. But in the frontier town of Xultek nobody bats an eye. Exact same character doing exactly the same things. (Actually western adventures would probably work really well, assuming the GM makes the effort to lose the six-shooters and the locomotives, and turn the evil rancher with the job into a self-proclaimed God-Emperor of his teeming but otherwise insignificant city)
S&S is about solving challenges with daring and muscle. Neither technology nor magic should be able to replace muscle. The core character class of any S&S adventure needs to be the Fighter. S&S heroes need to expend real effort, and S&S should be steamy and sweaty. One painful discussion point, then, is magic items. The purist approach is to remove magical +1 bonuses and make heroes rely on their own abilities. Perhaps a sensible alternative is to reskin magic swords as just really sharp ones. If you currently play D&D as written and have no issues with gold having little purpose, then fine. But many players will have trouble adapting to a game expecting gold to just run through their fingers, wasted on wine, women and song.
S&S is also "not epic" in that there is no place for the moral hero. While nobody finds it fun to play a suffering hero, NPCs should not have the same luck. I feel S&S is excellent for moral dilemmas with no easy solution - and no cosmic retribution for choosing the low road. S&S heroes should never be chastised for choosing the selfish or greedy or easy out. That's not the same thing as requiring players to play evil characters. It's just that good isn't rewarded and evil isn't punished. You're welcome to still avoid evil deeds - no point in playing a character whose morals disgust you, just as long as you realize you're playing in an uncaring world and you can't and should not get sidetracked by starting to right wrongs just because. Many adventures (especially D&D adventures) are written with "good wins out in the end" but a surprising number of scenarios can be (re)used by just dropping this notion. (In fact lots of D&D adventures would have become straight up just better if the scenario where the bad guys can win is taken seriously)
S&S is not equal and not fair. Might makes right, and if the "heroes" happen to come out on top, that helps nobody, because they will likely just drink their stay dry and when they go broke, move on. And it certainly does not have to be politically correct. If you personally don't like the notion that race is very significant and deterministic, fine, but to many a core aspect of S&S is the notion that civilization corrupts. The longer your character's civilization has existed, the unhealthier your people are in mind and body. While old timer S&S writers were outright racist (so that northern caucasians were the most pure and people from faux-Rome and faux-Egypt and faux-Babylon, say, were the peoples most associated with degeneration and debauchery and dark magics) you can change that aspect. I just find removing it to be too simplistic (few protesters think to replace the core theme they dislike with something equally compelling.) Other not-fair things like hunger or slavery or gender inequality are probably things you're able to see as tools not obstacles, otherwise why are you into S&S in the first place...
You say old fashioned. In the case of S&S, that's a good thing. S&S should be a "simpler" world where there's a limit to how far intrigue and talk can take you, and there's a point when pure action needs to be applied.
A game like D&D 5E is actually very well suited to S&S. However, if your players are currently enamored with high-level play and its spells and gadgets, you might want to hold off or choose other players. In fact, I wonder if D&D players aren't having a harder time acclimatizing to S&S than players of other systems...?
Random list (with only one item right now, since I already used Westerns):
* Journeying to the center of the earth is very S&S! Primitive and retrograde!
Yes, acknowledging that S&S heroes might not do it because it's the right thing to do is key.
Start off by having them save their own lives is another good thing. So attack them! Don't bother with much of a back-story, they can sort that out at the campfire afterwards!
If they decide they want to find out who's behind the attacks, fine, you have your story. Just be aware it's a very S&S thing to just shrug and move on "it's not my war". On the other hand, it's also very S&S to be forced into doing something. What's railroading in regular fantasy is a trope in S&S. (And it better be. You don't exactly have the "look the villagers are suffering, somebody rescue them" hook to play)
I wouldn't hesitate tempting them with their base instincts. If those attacking did so because the heroes stumbled into a battle zone, and the soldiers just assumed the heroes worked for the other side, they might inadvertently "rescue" a princess from her captors/kidnappers. A beautiful royal woman is worth more than entire cities for petty kings, but the heroes might just take her for themselves, or they might want to bring her to the attackers (holding no grudge for being attacked, seeing that all those 30 men paid for their mistake with their life).
It's kind of a sandboxy experience. Sure if you offer a ruined tower rumored to hold a giant ruby, no good player will just waste all your preparation by skipping it. But it's important to not judge choices. How otherwise enable players to truly the whole spectrum from selfless to selfish. (That's still not "evil". If your player starts torturing or raping, feel free to just stick a dagger in him. He can't very well complain a swift and nasty death isn't a S&S trope!)
So yes I feel D&D works really well. It's like playing a murder hobo with an unusual emphasis on the "hobo" part, and encouraging people to just live life to the fullest because it can end at any time.
If you play with downtime and building churches and guilds, this will be hard for you. But a murder hobo has no home and builds nothing lasting. Which is why I feel it can be a mistake to nix the gold for equipment mini-game that was a part of D&D previously. You can't fault players to want to build something, and to me it makes much more sense to build onto your character than the riches and kingdoms that will slip between your fingers eventually. (Sure you can do that with swords too; it's just that with the simple tweak that is "you gain quality not magic bonuses", I find that the game works for you and not against you). Plus, money is a far weaker motivator in a game than in real life. S&S heroes are supposed to risk their lives for mere gold, and just saying "you can carouse harder with more gold" is just not enough for many players. Enabling players to convert gold into game stat upgrades (if not actual items) actually works well for many gamers.
In fact, if you want to talk real hard-core old-fashionism there's the gold for xp paradigm. Heh! Nothing explains the greedy behavior of S&S protagonists better than if it is their players' key to leveling them up! It easily provides motivation for most to risk their hero's life and even throw it away sometimes!
In the end (an end I think ttrpg players will reach much faster than, say, comic book readers) you probably will want to fight for something greater than yourself. After all, if your character starts each adventure from zero, it will be hard to build any campaign sense, and eventually you're going to tire of "random" one-offs.
Whether this means surrounding the heroes with families and concubines that are cruelly removed from them to motivate them (easy to overdo; don't want the heroes to go fully nihilistic), or whether it means slowly unraveling a cosmic dark horror that is slowly eating the entire world (so that, again, you basically have no choice) I can't say.
Some games settle for playing until a king or warlock has been defeated. No need or desire to even reach the higher levels (even though a level 16 S&S Fighter cannot fundamentally do anything a level 4 Fighter can't; he can only do it far faster and more lethally)
