A player who beats the emperor may challenge for the throne by dice roll-off.
How it works
The first emperor is chosen by ballot (suggested via painting competition) and holds Rome. If the emperor loses a battle, the victor may challenge: both roll off, emperor +2; if the challenger wins he becomes emperor, the old emperor is slain and loses Rome and another province, and may retire or name a successor.
A challenge is resolved between the current emperor and the victor of the last game by a dice roll-off, with the current emperor adding 2 to his result.