Imperia Online is an existing real-time cross-platform strategy game with 30 million players, in which you start as the emperor of an undeveloped Province and you basically build everything from there - technology, military might, etc. As it's a MMORPG you're up against other human players and can trade resources with them, to partner with them or dominate them in the end. (I suspect Putin is an old hand at this title.) Game Troopers is a respected developer on Windows Phone and this is their polished client for the MMORPG.

From the Store description:

• Join thousands of players in an universe that never sleeps!
• Take control of your state and expand it into a mighty empire!
• Recruit soldiers and command huge armies into epic battles and crush all those who oppose you!
• Create your own royal dynasty and use it to govern your provinces and to lead your troops into battle!
• Make friends, join alliances and become the Lord of the entire medieval realm now!

Imperia Online is а massively multiplayer online game (ММО), set in the times before gunpowder was invented. These are the times, when the peace is ensured on the edge of the cold steel blade, the heavy cavalry and the archers with long bows.

Earn 20 in-game XBOX achievements to prove your awesomeness.

A couple of promo screenshots, to give you an idea. Note the mass of numbers across the top of the screen - at the end of the day MMORPG are heavily statistic-based - and a perfect match for freemium, of course:

You can grab this for free here in the Store, but note that it's freemium, so there are plenty of chances to spend money inside the game instead.

There's also a short, cheesy promo video for it: