I've long been dissatisfied with the mundane ways fantasy RPGs portray dwarves (or dwarfs, whatever floats your boat). They are, more or less, short, stocky, grumpy, bearded humans, except that they live underground and are greedy for gold and gems. Like REALLY greedy for them. They're sort of gnomish but way more industrious. And, sure, maybe they have other differentiating aspects. They have knowledge of the underground spaces, can see in the dark, detect slopes, suss out new construction, and all of that, sure. But in the end they're just little people who have some quirks. All of those quirks provide ways to differentiate their powers and abilities from other playable races, though I've never felt like it was really worth not just being human. Even DCC has this problem, sadly, and I've never quite understood the reason for the sword-and-board ability for dwarves in that ruleset. Seems like any warrior should be doing shield attacks, right? Mostly, it seems (again) just a differential power, with no reason for being except for "Not a Human." I won't even get into elves and halflings, now, because they tend to suffer from the same, "Like a human, but..." problem.
What if dwarves were weirder?
I like to think of dwarves as being more like the mountains themselves than like the men in the mountain villages. In fact, I think about giants the same way. They are children of the earth. They are born of the living stone (maybe literally "living") and take from it their flesh and bones, their character, their sense of the world. Different stone means different tribes. The granite and basalt dwarves are different. The dwarves around coal fields are especially odd (and flammable); and giants from those lands belch smoke and breathe fire. There are no sandstone dwarves, and none at all associated with sedimentary rocks: Only metamorphic and igneous rock will do.
Each dwarven "race" takes its character from its original substance. The dwarves of the Iron Mountains have grey skin, streaked with orange, and those who dwell in Cinnabar bleed mercury. The golden dwarves are beautiful and pliable, and desired by all. They hide themselves away, hidden from sight, protected from being stolen. Dwarves are of the flesh that is not meat.
A punch from a dwarf is like getting hit with a stone, and they have their own schools of unarmed combat. Such is the war they wage against each other, but they mimic the ways of humans to keep their true fighting traditions secret.
Dwarves cannot abide mortar and concrete. It smells of old death, and seems like an astonishing perversion of their very substance. They hate human cities for this reason. In every human habitation, they try to teach the natives to work stone properly, and with reverence, so that they can fit it perfectly without any cement whatsoever. But humans are stupid, and willfully ignorant. They can't take the time to learn, nor the time to coax the stones into their proper shapes. It takes a long time, and they are so short-lived.
Dwarves work stone more by persuasion than with blows of a pick, or chisel and hammer. They speak to the stone as they shape it, pressing their flesh into its flesh, and shaping it more like a smith than like a carpenter. Rather, more like an animal trainer, than like a craftsman. The stone listens. The stone speaks. The stone remembers, else how would the dwarves be born?
All the wizards want their secrets. All the elves want to steal their nobility, the mithril dwarves. All the humans pretend that the dwarves are just little, hairy, grumpy humans, perhaps from Scotland. They refuse to understand how wrong they are. They trade in the bones of the dead, looted from deep burial grounds. They will count a reckoning, later. Stone is patient. Stone can wait. Stone will not forget.
Dwarves (and giants) are the bones of the world, its blood and passion, and they have all the time in the world.