I do know that there is a mod for Rome II; however, a mod about Constantine would be better on Attila due to the features in the game, like renaming Cities, and the fact that they actually have Constantinople in the game. Still wish they added the ability to cede and request territories but that is another story.

Also the religion aspect of the game helps a mod for Constantine; although, I could have sworn less than 25% of the empire was Christian when he converted.