The connection between role-playing and the world of Nehwon goes back far—as far back as the Nineteen-thirties when Fritz Leiber and Harry Otto Fischer exchanged letters relating the exploits of their two “player-characters”, Fafhrd and the Gray Mouser. Leiber was Fafhrd; Fischer was the Mouser. According to Leiber in his foreword to Night's Black Agents, written in 1946, the first words written came from Fischer: “For all do fear the one known as the Gray Mouser. He walks with swagger 'mongst the bravos, though he's but the stature of a child,” and ended with:
Anyhow, they met, and the saga of how the Gray Mouser and Fafhrd of the Blue Eyes came to the innermost vaults of the City of the Forbidden God and there met death in the moment of victory in no common fashion, was begun.
Leiber goes on to say: “My imagination was enthralled and I responded with a fragment hinting at some further exploits of the two strange ruffians. With subsequent letters, the saga grew.” The two played a game of story-telling with each other with these two characters.
In the Nineteen-seventies, role-playing games, as we know them, came to be—the most famous of which, of course, was Dungeons & Dragons. In Gary Gygax's famous Appendix N, in the AD&D Dungeon Masters Guide, published in 1979, he includes Fafhrd & the Gray Mouser not only in the list of inspirational readings but states that Leiber's stories were among the “most immediate influences.” It is widely speculated that D&D's thief class is heavily base on the Gray Mouser. (The other chief contender is Cudgel from Jack Vance's Dying Earth series.) The Nineteen-eighty Deities & Demigods includes three literary mythoi among the myths of history: Cthulhu, Melnibonėan, and Nehwon. Its Nehwon mythos included stats and write-ups for both Fafhrd and the Gray Mouser, many of the gods of Nehwon, and many of the monsters. In its introduction, it says of Lankhmar: “within the walls of the city lie everything an AD&D player could ask for.” Apparently, even in the early days of the game, the writers recognized the affinity of Lankhmar and the D&D style of play.
For a little over a decade starting in 1985, the publishers of AD&D published a series of supplements and adventure modules for the world of Nehwon. Fourteen products were released in total. (see Dungeons & Dragons.) I have heard it said across the Internet by many that reading a Fafhrd and the Gray Mouser story reminds them of a D&D adventure. This is not surprising considering that writing about these two characters was a game of fiction between Fischer and Leiber. The spirit of adventure was within the pens of these two progenitors. And yet, playing a Lankhmar game using D&D rules feels more like the world of D&D than it does of Nehwon—at least to me. It is a strange asymmetry that Nehwon has provided richly to the richness of D&D, but D&D can only give so much back to role-playing in Nehwon. There are many issues at hand, but I believe the biggest obstacle is that D&D uses a magic system based on Jack Vance's Dying Earth stories, and the magic of Nehwon is ritualistic as opposed to pre-memorized, whip it out at whim, spell slots. (see my articles on Nehwonian magic.)
The last D&D Lankhmar product came out in 1996 and for another decade there was a dry spell for Nehwonian role-playing until Mongooses's RuneQuest picked up the license in 2006. It was a short-lived venture lasting only until 2009 with only four products released, and of those four, the main sourcebook, Lankhmar, was remade into Lankhmar Unleashed. It was as if they had no faith in their original launch of the line. As it was, nothing more came of it afterward.
Nearly another decade had gone by before another company took a stab at Nehwon, and in this case, it was two! In 2015 both Dungeon Crawl Classics and Savage Worlds gained licenses to Leiber's works and started releasing role-playing sourcebooks, supplements and adventure modules for the setting. It is as if we are now in a Lankhmar RPG renaissance! DCC as of 2019 has released three products so far (see Dungeon Crawl Classics) and has funded an ambitious boxset through DCC Kickstarter. Savage Worlds so far has eight major products and numerous one-sheeters or other supplements. (see Savage Worlds).
As I have mentioned, D&D's magic system is all wrong for Nehwon. Also, its class system is a bit restricting to literary characters that dabbled in multiple interests. Fafhrd was a singing skald and the Mouser used to be an apprentice to a hedge wizard and still dabbles in sorcery from time to time. In D&D terms, Fafhrd would be a Fighter, Thief, Bard, and the Gray Mouser would be a Fighter, Thief, Wizard. Both D&D and RuneQuest forced the setting of Nehwon into their own rules-sets, like square pegs into round holes. I have not had time to explore Savage Worlds or Dungeon Crawl Classics efforts yet but in many of the comments from 2009 and 2010 to my original post on this subject (not to worry, you are not missing much from that post and the comments have been revived below) the commenters have recommended Savage Worlds as being a good fit. (For further reading on this subject, see Rose Bailey's Swords Against Editions.)
Nevertheless, I would like to see a company that would create a ruleset for Nehwon-style play specifically, as Robin D. Laws did for The Dying Earth. I am a firm believer that game mechanics provide the foundation for stylistic fidelity for role-playing with literary sources. The combat mechanics determine the feel of role-playing combat, the magic mechanics determine the feel of role-playing magic, and in general other mechanics can shape the roleplay of the game. The stories of Lankhmar have already informed my own homebrew system, the adventure scenarios that I have created, and how I run my games. For instance, I use a ritual magic system of my own design. If I could afford the license, I might take a stab at it myself! As it is, the adventures of Fafhrd and the Gray Mouser deserve their own game system.
Here is a list of RPG systems that have been recommended in the discussion below: