I'm going to go with cowboys and indigenous peoples dude!
I'd like to see a decent update to Boot Hill, as long as it captures the Old West feel and is true to the genre. That is straight up Wild West, not D&D in the Wild West, or horror in the Wild West etc.
How about something based on bronze age Greece and Rome.
Or something based on various what if scenarios...
What if the Aztecs had magic and defeated the Conquistadors...
What if the Vikings survived in North America...
What if there were no gods... only spirits...