Dwarves are a playable race in my Horizon games, yet even this statement comes with a qualification - as, like many other peoples of the realm, they are deeply fractured and scattered.
Originally a more-or-less united people who lived and prospered in the mighty kingdom of Aluren, at some point they discovered something so gruesome and mind-shattering within the deep tunnels of Moradin's Crown, that it altered the race forever. The mass exodus and sundering of dwarvenkind that followed is known as the Grim Reminder and stands as one of the most enigmatic and history-changing events of Thessean history.
The dwarves the players can play are the ones known as Turim (the Ignorant) - members of scattered communities, often either very isolated or intermingled with humans - who were not privy to the Grim Reminder's secret and have thus rejected the exodus to Kharad. These dwarves can be played with any relevant statblock the game system provides.
The actual, numerous race of dwarves, secretive and proficient in arcane arts and gem-cutting, live (at least on the surface) within confines of the Kharad archipelago at the southern cape of Thessea, under protection of the Borean crown.
The Kharad dwarves are privy to a dark, fundamental secret that, if it comes into the wrong hands, can shatter the very foundation of order and civilisation on the Horizon. They are, therefore, cannot be played and are NPC only.