It's been done by others (GURPs comes to mind), but a Paratime-style campaign would be fun: A gazillion parallel Earths. everything from Dino-land (with or without humans primitives) or otherwise to TechoRome or some other there-wasn't-a-dark-age world. Had this idea a long time ago of timeline where Alexander the Great lived another twenty years, dying of malaria on an expedition to find the source of the Nile...
These two, especially the Cold War era would be great. I can't think of one Cold War era RPG other than the James Bond RPG, which is a very specific type of RPG. A more generic Cold War secret agent/action hero/private investigator/etc. game would be cool - and something that isn't already done to death in RPGs.The Thirties, before WWII.
The Cold War.
Actuall, CoC does (or at least did) Cold War era as well, with Cthulhu Now (80s). Not sure if they have a newer version, I don’t recall seeing it.These two, especially the Cold War era would be great. I can't think of one Cold War era RPG other than the James Bond RPG, which is a very specific type of RPG. A more generic Cold War secret agent/action hero/private investigator/etc. game would be cool - and something that isn't already done to death in RPGs.
For the Thirties game, I would lean on Indiana Jones and Film Noir, not Horror (Call of Cthulhu already does that).
This all with a caveat that do these only if they do not hamper the Traveller RPG line, of course.