This mod is for Rome Total War v1.5. You will be able to go i nto the battle and fight as any one of the soldiers. Archer, horseman, spearman, etc. You will be able to climb ladders, seige towers, and do anything that a normal soldier would do. All the normal things in Rome will be do-able.
The ways to get onto large walls will most likely be chaged to support the mod. Buildings will not be enterable. You will be able to rome free from you unit group and shoot arrows from a distance or go crazy and attempt to attack an army from behind alone. While you are in the RPG mode your army will follow the orders you gave. At any time you can exit the RPG mode and give orders to your troops.
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