A New Kind of 4X
Sorcerer King is a new direction for 4X game design, pitting the player against a single overwhelmingly powerful enemy instead of a set of evenly matched factions racing for abstract victory conditions.
Think of the Sorcerer King as the evil mage who won the last traditional 4X game. He has already conquered the world. His enemies (including you) are scattered, their armies broken and cities torn down. His dark minions have free reign to terrorize the survivors everywhere except a few tiny outposts of civilization (like the one you start in) too insignificant to crush.
Sorcerer King is built around the concept of asymmetry. Your goals (kill the Sorcerer King) are wholly different than the Sorcerer King's goals (destroy the shards and therefore the world). The rest of the game revolves around this central concept.
The Sorcerer King doesn't play by the same rules - he operates on a completely different level than your scarce resources allow you to. A sophisticated "Game Master" AI controls his forces and other events in the world, managing pacing and generating threats to ensure an engaging game from start to finish.