Have you heard of Worlds of Magic? It's a fantasy 4X game, with a ruleset based on the d20 Open Game License modified for strategic needs. It aims to be a spiritual successor the old classic, Master of Magic.
It's currently in Alpha stage. You can already check it out and play a combat demo:Here is a web-based build
(100+ MB, can load for a while)Here you can download it
And a screenshot teaser: