Europa Universalis: Rome - Vae Victis is an add-on for Europa Universalis: Rome and requires the original game to play. Besides technical improvements like a revised AI and interface it mostly focuses on new gameplay mechanics. The most important new feature is the Senate for Republic nations which takes part in the nation's political direction. Now the player needs to take the Senate's composition into account respectively actively influence it. They also give tasks to the player, e.g. to conquer a province until a certain date. The same is true for tribal or religious leaders in other form of governments.