[Alneyan]

There is actually another way to do this, without using a Mod of some sort. You should start up the game with all other Empires disabled (perhaps under AI control while the AI is disabled?) and then play on your own, bringing your Empire to the desired level. (Or another Empire for this matter)

This way you would have a much stronger Empire, and its advantages could go from a few turns to the whole tech tree and a hundred sphereworlds fully developed with Cultural Centers. There was a Scenario a bit along these lines, where you play an Empire with two mere planets against 18 other Empires at war with you. So you have to rebuild your Empire from scratch, and you can capture some of your old warships drifting in space. It is Awakening by Geoschmo if memory serves right. (I cannot even recall where I found this jewel. *Grumbles*)