The closest similarity to this game that I can find that already exists is ogame, an online spreadsheet rts.  It was addictive and sucked away a few months of my life, but I quickly realized the futility of it.

Having joined the universe months after it had been made, I was drastically far behind and once I was past the newbie protection point cap, I kept getting smashed by people with millions of points compared to my few thousand (points were kept based on resources spent so high scores meant huge, teched up armies).  There was nothing I could do except sit idly by while I kept getting smashed to bits.  When a new universe was started, I joined but it took so much of my time to stay competitive I finally gave up on the game.

As someone very interested in Society, I'm very curious as to how these issues would be addressed.  If the bulk of the game is in the WW1 era and someone joins the game from scratch, how can they possibly compete?  I understand that only 25% of your land can be attacked, but shouldn't these newer players have the ability to expand without fear of easy annihilation? Otherwise it becomes simcity with only 3 cities and human neighbors and would quickly get boring.

I'm not suggesting that a new player should be able to single handidly overthrow the leading players, but I hope that the new players can join midway through a world and still enjoy the game, rather then having no influence on the game's outcome at all.  Maybe players starting in the WW1 era would have civil war era equipment right at the start and could ally with an empire willing to catch them up?  That way they werent drastically far behind and still had an influence on the outcome of the game, because what empire is going to pick up a newbie in medieval when it adds to the number of attackable provinces?