re super-heroes
Given the convergence of comics and pop art and youth culture in the '60s, I can imagine a loosey-goosey supers game. It wouldn't be inspired by wargames, but maybe traditional boardgames or card games instead.
I still don't think supers-as-the-original-RPG is very likely, but maybe that's just bias from how things are in reality speaking. Reaching for a plausible reason for a 1974 comics TTRPG starting the hobby, the most likely scenario I see is what I call the Magic Effect. Some staffer (no doubt in accounting - lets call him Garfield Richards) comes to the execs at, say, Marvel and sells them on doing a print run of this weird new "roleplaying game" prototype he's already gotten the bullpen addicted to. The thing unexpectedly takes off with readers and rapidly gets much more funding and staff thrown behind it, leading to DC quickly imitating it with their own innovations and opening a new front for the intercompany rivalry to play out on. Their dual successes lead to the roleplaying concept rapidly diversifying into other genres the same way in our world, but this time starting from comics - and maybe the comic industry as a whole gets enough of a boost that it's much less moribund going forward from there.
Speculatively, the earliest RPGs in this timeline wouldn't be boxed sets or magazine-sized booklets, they'd be printed in comic book format, complete with full color throughout, shoddy paper quality that won't hold up to extended use, and the art isn't going to be the amateur-hour stuff seen IRL, it'll be whichever bullpen artists get assigned - and if they're addicted during playtest that might include some very big name volunteers. Real-world V&V was boosted a fair bit by Dee and Willingham's art - imagine what a having art by Kirby or Ditko or Steranko would do. They'd probably be weird experiments with formats and release styles - maybe the "core rules" are jammed into one high page count floppy that keeps getting reprinted, while expansions and hero/villain stats take the space of what would have been backup stories in regular comic issues, boosting sales for both comics and games and driving collectors nuts. The print runs (at after the first) would be large than normal by RPG standards, but the fragility of the floppy format means finding mint copies would be difficult and result in high back-issue prices.
This probably wouldn't go on for long before more durable formats got adopted for the games-first crowd, resulting in more recognizable game books. Maybe not so much on boxed sets though, and knowing the way the Big Two skeeve for for profit they'd likely still stick some gaming content in their comics to encourage buying an extra copy now and then. After all, comics are relatively cheap still (and could stay that way longer with higher circulation/demand) and xerox copying (especially the rare color copiers) was not all that inexpensive, somewhat discouraging piracy. Stuffing a particularly juicy big of crunch into a comic might be the early equivalent to the variant/foil/hologram covers with polybagged collector cards BS seen from the 90s boom onward. Adventures based loosely on the comic plots themselves could be serialized over multiple issues, perhaps showing "off page" stuff going on with supporting characters while the main action is happening. Oh, and the crossovers, so many crossovers. I can hear Garfield Richards chortling down in the accounting department.
And of course, there'd be tons of comic purists bemoaning the loss of page count to this "roleplaying" nonsense and how these "gamers" have ruined the hobby forever, yadda yadda yadda.
Be a very different world, and even with non-supers-based RPGs things might look odd because of expectations shaped by the DC/Marvel games.
