Haven't heard if anyone has succeeded in doing any of the special missions in the game so far. There is at least one for: Romans, Pontos, Aedui, Epeiros, Seleukids, Makedon, and some similar elements can show up if you do certain things for Baktria or Pahlava.

Just wondering if anyone has succeeded in any of them.

But warning - don't read any further if you don't want to hear about anyone else's experiences with them.