... Well, I think many of the genre conventions were established enough that there was even one tabletop Steam Punk RPG that predated the publication of "The Di

... Well, I think many of the genre conventions were established enough that there was even one tabletop Steam Punk RPG that predated the publication of "The Difference Engine" (1990): Space 1889 - (first published in 1988/89) However - I think it was essentially just a convergence of cultural zeitgeist within about an 8-year period. (Myself, I preferred "Castle Falkenstein" (1994) - but that was because I liked just about anything Mike Pondsmith/Talsorian released)