A late-night brainstorm on the Dwarf and Elf character races. It's evident that I've put more thought into the Elves so far. I think I will be giving these races different names at some point, though they may still be known throughout the world as Dwarves and Elves.
Dwarves are a matriarchal race, descended from Oreads and humans. After generations of mining, Adamant Dwarves (the dwarves most people are familiar with) are saturated with adamant, a magnetic metal that absorbs magic. While inherently magical, Adamant Dwarves are unable to use magic and are very resilient to it. Volcanic Dwarves, sometimes called Molten Dwarves, are dwarves that were trapped in a volcano during the God’s War. These dwarves survived by forcing elves that were trapped with them to either use magic to replicate sunlight or to become more plant-like and use photosynthesis to convert poisonous gases to oxygen.
Surface dwarves are generally human-sized, though the deep Dwarves (typically, Adamant Dwarves) are affected by stronger gravity and are normally shorter, stouter, and more solidly built (while gravity on earth diminishes as you go further underground, Kirinioth’s gravity grows stronger as you get closer to its adamant core).
Elves are also matriarchal and are descended from Dryads and humans. Elves live in symbiosis with the forests, and Elven Tree Singers shape the trees of the deep forest into their cities. Ash Elves and Cinder Elves are fallen elves whose Dryad was burned. Most are insane, and some are cooperative with Volcanic Dwarves. Kirinioth Elves are often solidly built and are not frail like typical fantasy elves.
Different types of elves are descendants of dryads of different trees. The elves are not an elder race, but some are extremely long-lived (lifespans mirror that of the tree they are descended from). Elves can mate like mammals, but in some rare cases will seed like a tree. Rarely, these seeds may grow into a Dryad. Being a hybrid race, there are no Half-Elves. Elf children may take on cosmetic traits from either dryad, elf or human parents, but from a game play standpoint, each child is considered an elf (if both parents are from a different tree lineage, they will take on the traits of the strongest line). Some Elves are capable of photosynthesis and can breathe CO2 in the absence of oxygen but will require something to emulate sunlight.
Possibility: Elves have bark-colored skin and leaf-colored hair. Some elves can harden their skin as a natural bark skin effect. Elves and dwarves are traditionally allies, and the best smiths in the world are those dwarves and elves that have apprenticed with one another.
I should probably add something here.