Dwarves, Automatons, Kobolds, Minotaurs (my fort is going on really well, thanks for asking),Drows, Elcars, Valut Dwellers and wizards are playable in fortress mode
The others are only playable in adventurer mode, and can trade with you or attack you in fortress mode.
Of these races i've only played with minotaurs, that barring the naming of the nobles (and maybe their physical streghnt) are really just big dwarves, and i have traded with drows (bunch of nice guys if you ask me, love buying wood items) (and i have some problem with silver xelics, i dont know what i keep selling them that is so ofensive to their traders), the other races i've never even saw (I think most of them died in world gen, and some times i get dwarf leather items for trade), but i know that kobolds are really different and hard to play with, and that automatons and wizards have many castes and powers (and the dwarves too, since they come from the genesis mod)
Oh, and if you take the latest version of the mushroom kingdom and put in your dwarf fortress, Toadstolls, koopa troopas and goombas should be playable too (and shyguys become a new goblin-like civ), it should work without any conflict, but you will probably need to gen a new world
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edit.
Hey, i was trying to put the minotaurs graphics in the game, when i saw that the files were already there, and when i looked i saw a bunch of other graphics, you just have to turn them on in the init file, oh, and i recomend a new tile set as well (im using goldplated so far)