I'd use descriptors for culture, something like militaristic, seafarers, nomadic, mystical, enlightened etc, which can layer on top of any race/background. They could even be light enough that two can be chosen to describe a culture. A mystical-nomadic culture might wander over a large swath of land and have magic as a common part of their culture while a militaristic-mystical culture might have a requirement to train in simple weapons and light armour with some battle magic as part of growing up. Perhaps typical dwarf culture is militaristic-craftsmen to get that fighters who are skilled craftsmen feel to it. The basic building blocks could also be examples if you feel like you can't quite get that roman culture feel from the provided cultures.
It's a lot to create but the pay-off I think would be great once completed.
Yeah, I had slowly been doing something similar (and influenced by Runequest, Rolemaster, and Harp). Some examples that I had been considering were:
Barbarian (could probably use another term), Nomad (Foot), Nomad (Horse), Nomad (River), Rural (Farm/village), Urban
Arctic, Aquatic (Underwater), Coast, Desert, Forest (Cold), Forest (Temperate), Hills, Grassland/Savanah, Island, Jungle, Mountain, Wetland (Marsh/Swamp), Woodland, Underground
Special; Mageocracy, Military, Monastic, Theocracy, Street.
Also, Rich Howard had a good start in his article,
Ultimate Adaptability, for a variant Human based upon culture which was posted both at All Things Gaming (his personal gaming site) and at Tribality. He does, however, keep attribute bonuses based on culture. I would also look to Gygax's AD&D Barbarian class (in Dragon or 1e Unearthed Arcana) for cultural skills and weapons, and David Howery's AD&D article, Tracking Down the Barbarian, from Dragon for cultural armor and weapon proficiencies.
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