By the 1970s the Sword & Sorcery boom was in full swing, with books and comics both adapting older works and creating their own. After Conan the Barbarian in 1980 movies got in on the act, and it was inevitable that the genre would extend its reach into other media. One of the most influential on the longevity of the style was the advent of fantasy games.
Fantasy role-playing games grew out of the tabletop warfare simulations that had been a hobby since the 1780s and had grown immensely in popularity through the 19th century. It was after WW2 that the market for wargames exploded, and soon enough people started looking for new things. The popularity of fantasy in the 60s and onward provided an obvious outlet. Tolkien’s Lord of the Rings trilogy provided many examples of epic battles, and imitators like Sword of Shannara doubled down on the big war sequences in line with the tastes of the time.
Because Tolkien, for all his heroic trappings, was not a fan of war as entertainment. He had served in the trenches of the Great War and lost friends. He did not glorify violence in his work. Other fantasy authors were, however, glad to make up for that. The strain of violent, darker “heroic fantasy”, descended from Howard and the pulp writers, was there to step into the breach.
Dungeons and Dragons was the first real fantasy role-playing game. After first attempting to make rules for fantasy armies, Gary Gygax and Dave Arneson created rules for playing an individual fantasy character, and the tabletop RPG was born.
Despite the amount of Tolkien influence on the worldbuilding of D&D – halflings, elves, rangers, etc – the gameplay owes much more of a debt to Sword & Sorcery tropes and styles. After all, while many players aspired to fight evil and do battle against powerful foes in a fully-realized High Fantasy realm, the truth of play was much different as the game was first written. Players dreamed of high fantasy, but that’s not what the game really simulated.
Because the world and play of D&D was pretty much the model for every kill-and-loot game since then, whether on paper or in video games like Gauntlet or Diablo. The whole point was to make your way through an underground maze, kill monsters, and take the treasure they left behind. There was some hand-waving towards good vs evil, but really, the moral waters of the original game were pretty muddy. It was a world with gods and heroes and devils and sorcerers, but rather than strictly good vs evil, it was much more players versus everyone else.
That is much more an S&S kind of setup, and even the image on the famous cover of the original Players Handbook depicted a scene right out of a Howard story: the heroes raiding a temple of lizard men, looting the treasure as they planned for the next attack. That is a scene that could have taken place in any S&S tale from the pulp days, and there are any number of tales by Howard or Leiber about the brave heroes venturing into some ancient ruin or haunted wilderness in search of gold and jewels.
In its earliest days, D&D required a very S&S kind of play – characters wandering from ruin to ruin, plumbing down into caverns and lost temples, killing anything in their path and then looting anything that was not nailed down. That is not a High Fantasy approach, it is explicitly rooted in the moral ambiguity and noir sensibilities of Sword & Sorcery.
When D&D blew up in popularity in the 80s, it got a whole generation accustomed to the tropes and feel of the pulps, and sent a lot of them hunting through libraries for classic works listed in the D&D bibliography for inspiration. I think more than shape the course of the genre as a whole, D&D had a big part in making sure there was an audience for it. A generation grew up dreaming about dungeons and ruins and swords and magic and monsters, and that made sure that the appetite for Sword & Sorcery adventure stayed fresh.