Elder Kings is an Elder Scrolls themed total conversion for the Paradox Development Studio game Crusader Kings 2. It allows players to live out their dreams of ruling one of the great realms of Tamriel and leading their dynasty through it's various eras and challenges. While still effectively a Work-In-Progress Project, Elder Kings still offers one of the biggest gameplay experiences available for a released CK2 mod!
This mod is amazing, I'd say it is the best mod for CK2 I've ever seen. Here is why:
1. World - it's really huge (1 whole continent and a part of the 2n one); lore-accurate provinces; pretty and realistic terrain paintings; on-map 3D buildings are unique to each race.
2. Races (cultures) - you can play roughly 25 races, most of them with unique portraits and culture traits. You can play as a "normal race" or as undead Draugrs, extinct Falmers, Oblivion's Dremoras and more.
3. Traits - apart from vanilla traits, each character bears a birthsign and a race-determining trait. There are 15(!) professions (vs 4 in vanilla), each having four levels of mastery. Also, being an immortal vampire or lycanthrope is determined by trait. Minor changes in genetic traits and improvements in illness system.
4. Titles - awesome "forfeit and unite" system implemented for crafting High Kingdoms, which do not exist (even de jure) until you unite some "minor" kingdoms (do not confuse with duchies) under your rule and by Decisions window choose to merge them into one High Kingdom. Most of empires are crafted the same way, and a name (and banner) of an empire depends on which High Kingdoms you posess.
5. Events - you can undertake a pilgrimage to High Hrothgar and learn the goddamn Thu'um (if you're lucky). Sheorogath can pay you a visit - in one of his chests you can find nothing OR i.e. a strong claim on the Empire of Tamriel... Finally it may turn out that you are a Dragonborn. FUS-RO-DAH!
6. Magicka - it's a part of trait system and it yields a spellbook. Rituals, healthcare and oblivion invasions await you.
7. Province improvements and councillors - tons of buildings (ready to be described by some desperate guy :D ). New interesting jobs for councillors, one of which is almost necessary to forge the Empire of Tamriel. Also, there are minor titles you can give to people by Honours system - it gives you some fine profits.
I'm out of space, just go play it already :D