I have changed just about every file over the years (we are closing in on a decade), not to mention all the LH's, units, etc... that have been added. I play it a bit everyday, unless there is a new great game like Final Fantasy, Warhammer, EFZI, etc..
I would guess that this is the case with a lot of people, I have actually thought of loading my game, but the size is probably extremely large and there is no special theme.
My game is 31 CIVs, all the original Conquests civs except the Americans are replaced by the Sioux. 1000 turns 9992BC to 2258AD. I've balanced the game over the years, advancements are paced, 25 turns is the fastest that you can research (units aren't always obsoleted from the time war is declared to the time of the actual battle), I've added mechs and genetically modded units in the last couple centuries, I've added some mythical units just because the units are so good. I use different workers for different jobs, so you may see several different workers for one civ on the screen at the same time.
Sorry, I've started to ramble, but it is faster than downloading the whole game.