Joining Nights Watch should be an option (as joining other factions). Nights Watch campaign overview example: join, training, scouting beyond the wall, smth epic, end campaign, you become a hero and well known in Westeros, so they send you to recruit (radial quests like in the end of DB). If you concentate only on one area it's highly possible to make the mod impossible to expand. First a heigtmap should be generated for a large portion of Westeros (for LODs and a guideline for expantion). Creating a small portion of high detail land (a city or a village, possibly a small quest (should be as original as possible, not just go there, kill'em all)) as a demo and to test/show your abilities, demo will help recruit more people (hopefully). Doing this kind of mod fully finishing small portions (with quests and everything) isn't very good idea. It's better to do a larger terrain work (fields, citie, villages, mountains, forrests) first, then interiors (general ones), npcs (general), quests (quests, q npcs, and q locations). Adding new items is very cool, but don't overlook existing ones (Skyrim doesn't only have snow and mountains, there are forests, fields, lakes well fitting in temperate climate (i mean summer, early fall in Eorope)). For a main quest line it's better to think of a new story line (before or after the series) so noone can complain about it not working with the books. Skyrim has an extended magic system (will be much cooler soon i'm sure with mods or dlcs), so the "modern" Vesteros with awakening magic doesn't realy compliment this system (if not including magic properly you might loose mage-loving players). If i were you I'd pose it as a sequel to the book, some 200-300 years later, so i'd have full freedom with a storyline (I'm thinking of using scripts to make a unique storyprogression for every new game, with dinamic relationships between factions and leaders, which could lead to wars, assassinations, and general powerplay for theoreticaly infinit time). For a city layout it would be cool to have to be able to travel on roofs (smth like assassin's creed(no wall climbing just roofs as it's quite easy to do)). Just my thoughts.