Grand Ages: Medieval
Grand Ages: Medieval is a game targeted at a niche of gamers, those who might find even classic history-based titles like Europa Universalis IV or Medieval: Total War lacking when it comes to the economic department.
It's probably not a game that you're going to spend too long playing online, and the AI is generally too soft for its own good, but Grand Ages: Medieval is the kind of game that, every time I sat down to play it, I'd lose time and end up playing for a half dozen hours or longer. There is perhaps nothing more rewarding that watching a tiny village grow into a mighty empire, and that counts double when the expansion happens through non-violent strategic thinking. It's not quite Europa Universalis, or even Nobunaga's Ambition, but it's difficult to think of a more accessible, effective grand strategy game than Grand Ages: Medieval.