Sometimes, awesome things just get more awesome. Such is the case with the Game of Thrones mod for Crusader Kings II, which has just posted a dev diary detailing a long-awaited addition. The expansive continent of Essos is under development for a future release, more than doubling the landmass available and introducing such locations from the acclaimed franchise such as Slaver's Bay and the Free Cities. Set sail for the sunrise and start brushing up on your Pentoshi—we've got more details below.
To the casual fan, Essos is the eastern landmass where Daenerys' (that's the white-haired girl with the dragons, if you have as much trouble keeping the names straight as some of my friends) storylines have all taken place so far. It's mainly dominated by city-states that arose from the ashes of the old Valyrian and Ghiscari empires, and they will run in the mod using the mechanics introduced in CK2's The Republic expansion. Thus, you will need The Republic installed to play as them.
The diary also speaks of new mechanics for ruins, since much of Essos is dominated by them. The possibility is mentioned of being able to colonize ruins—a mechanic that has never appeared in Crusader Kings, but is a staple of a couple other Paradox strategy franchises. As for what's not in (at least in the current, internal build): Qarth itself and, sadly, the Dothraki. Much of the continent is shown greyed out as wasteland, but the diary does promise that "the Dothraki shall be implemented in some way and we do have a basic plan for them, but that probably deserves its own full explanation later on." My guess would be that we'll be able to play them once the new mechanics coming in The Old Gods expansion are implemented. The pagan subjugation and rule by might systems would be a great way to model the rise and fall of Khalasars.
It may be a while before Essos is actually implemented, but until then, you can download the latest version of the mod and carve your path across Westeros.