Imperator: Rome is, much like any Paradox game worth a damn, capable of hosting an extremely wide variety of mods both greater and lesser in scale. The Game of Thrones-themed Century of Blood is a total conversion, for example.
This lovely Game of Thrones mod for Imperator: Rome will not only let you remake the series from the ground-up, should you be so inclined, but it will also let you feel first-hand what it's like to be a ruler in this grisly fantasy universe.
The complete changelog for Century of Blood includes changes and alterations to virtually every component of the core Imperator: Rome experience, and the mod's not even out of alpha yet! If you choose to go ahead and install it, you'll get the complete A Song of Ice and Fire makeover of the game.
This, of course, includes the introduction of the historical GoT Houses such as those of Starks and Lannisters, 44 appropriately-themed government styles, cultures, and religions, a complete Idea overhaul, expansion of cities, military unit and general combat revamp, and a whole lot more. In short, this total overhaul of Imperator: Rome is precisely that - a total overhaul.
To download this lovely little mod, just visit our Century of Blood Mod page and hit the appropriately crimson 'download' button. Be sure to follow the installation procedure to a T, however, as it does require more than a simple copy/paste job for something of this scale.
Good luck!