I think it would be very interesting to have a game mode option where the spell to create a new city requires not just Essence, but mana was well. This very simple change would have a huge impact on the first twenty (or so) turns of the game, because the mana can start at zero.
It means your Soverign will have an intial "Exploration" phase where he's wandering the wastes, scouting out a good location for his city while his mana bar slowly fills to the point where he can cast the renewal spell. It'll mean he/she does some early fighting, exploration, gets a feel for his or her surroundings before settling in. And not just your Sovereign, but also those of the AI/other players, so this exploration phase is *part* of the game, rather than merely being bad tactics where you fall twenty turns behind for doing a bit of exploration.
I think this would really help develop the game's feel and mood. Your Sovereign would be all alone in the wastes, wandering a ruined world, and the first thing the players would experience is the empty, hostile nature of the world. Thematically, I think this fits better than "Game Start, Loaded, City Built, Produce House and Military and Research" tripple whammy on the first turn. Doing it that way, my Sovereign feels like he was just plunked down in the middle of a green patch, and I would miss out on the feeling of accomplishment of actually restoring part of the world to life.