I have often pondered this. In the game, there are some features that are the same across most members of a Dwarven civilisation - one civ may have lots of Dwarves who are kinesthetically impaired and have broad noses and umber eyes. Another may have long hair and braided beards, and good creativity. There are already small differences and qualities that are civ-specific, why not on a cultural level?
Some civilisations from the desert could wear turbans and worship desert gods. Others from the forests could wear loincloths and worship various gods of the forest. The possibilities are endless.
The problem though is with Dwarves. Dwarves tend to always settle in the mountains, not on the plains or in jungles and so on. Humans are more versatile, so one could see them being a very diverse bunch indeed. Perhaps the Dwarven cultures could differ depending on the conditions of their home region - the level of savagery/evil/goodness, the temperature, proximity to the desert or the jungle and so on. You know, perhaps Dwarves who settled in evil regions, or regions that became evil over time, could become very pessimistic and worship negative gods such as gods of death and suffering. On the other hand, they could do the opposite and worship goodness - something that is sadly scarce in their homeland. They could make it a religious or cultural obligation to settle in evil areas and make them habitable again - like crusaders of a kind. The same in reverse could go for evil civilisations who worship darkness and wish to spread it, so they wish to corrupt good areas.
Perhaps every 100 years or so, the game could take all the main events of your civ's past into account and absorb them into a civ-wide "culture". As an example, if 10 hydras attack your fortress and cause terrible amounts of death and destruction, the civilisation would develop a deep fear and loathing of all hydras and offer more missions to adventurers to go and kill them. Other things that could be developed are hatreds or admirations of particular races or civilisations based on historical matter. Another would be the popularity of certain clothes or weapons - Dwarves in a civ might "take" to a particular type of axe or sword or shield, so their fighters will ultimately become some of the most respected users of those weapons. If most Dwarves or perhaps a particularly influential Dwarf takes to wearing a mask covered in pictures of clouds, masks with pictures of clouds on them of varying quality would gradually spring up and would "go into fashion". If enough time passes, or if something new comes along, maybe they could go out of fashion.
Among the Dwarves in a particular world, one could see civilisations such as (to quote a gentleman in a thread similar to this) the xenophobic renegade Dwarven kingdom who live in the arctic far north. They hold travellers and foreigners with extreme suspicion, and greatly admire hardworking, austere and severe people. Their recent war with the demon-corrupted arctic human civilisation to their southeast has led to a terrible civ-wide distrust and hatred of humans, and human travellers who cross through their territory alone are prone to being robbed or possibly murdered. The clothing of these Dwarves is chiefly thick and padded to keep in the heat, and usually features things like thick mittens, furs and heavy hoods. Their eyes are often narrow, their skin a pale grey, their hair a deep red and their lips thin and drawn. They are stocky and broad - usually strong in the upper body, but also quite plump to ensure warmth. Their faces are wide and flat, with short, thin noses. Their beards are often left in triple braids to emulate their greatest hero, famous for escaping from a human castle on three lengths of rope tied together, made from his own hair.
On the other hand, the Dwarves of the great Talonscar mountains in the lush broadleaf jungles are quite the opposite. They are celebrated traders and are widely-renowned as excellent carpenters and woodcutters. They have had an easier life having settled in such bountiful surroundings, and are more prone to valuing the qualities of moral fibre, skill when working with one's hands and aptitude for speechcraft. The Talonscar mountain Dwarves tend to wear very little, due to the heat that surrounds them, and prefer to walk around often stripped to the waist. Their hair is usually clean shaven, again owing to the heat, but their beards are left to flow freely for they believe that beards are sacred, and are their connection to the natural world around them. To mar or tamper with their beard would be a crime against their very nature, so their beards are often as low as their chests. They are, however, unusually tall for Dwarves due to them needing to run to hunt their prey, as hunting was once far, far more common than farming. Tattoos hold a special place in Talonscar mountain society, and often depict past glories and victories over local titans and jungle beasts.
I shall post this in the other thread in case this one dies.