I feel that much of the fun is in the reforms. Working hard to get the Marian reforms is really good role play and gameplay wise. Play as a different faction if you want. The recruiting system is great. I made on legion of Hastati, Principes, and Triarii, but by the time I reached Gregovia, it was half Gallic. I love how it seems so realistic that an army that took heavy casualties might recruit local soldiers to fight for them.