Because the mod has evolved over 15 years, there are several distinct versions. Choose the one that matches your game installation:
The most modern way to play is through the Rome Total Realism: Platinum Edition REMASTERED on the Steam Workshop. Alternatively, you can download the massive RTR: Imperium Surrectum (RIS) , a collaborative project between the RTR and Roma Surrectum teams specifically for the Remaster. For Classic Rome: Total War (Steam or Retail):
The definitive "classic" version. Available at ModDB .