http://www.simcity.com/en_US/faq
What is SimCity?
SimCity is the reinvention of the flagship of city-building simulations. With this game, every choice you make you will see it affecting your city, your region and the world within the game.
What’s new in this SimCity?
SimCity delivers unprecedented depth of simulation with the new GlassBox Engine, where everything is simulated, from up to 100,000 individual Sims in a city, to every Kilowatt of power pulsing through a region of cities. The model-like world and detail of the simulation make this the most responsive and personal SimCity ever. This is also the most expansive city management game yet where multi-city gameplay across regions delivers a larger playing field. Play a single city or up to 16 cities at once each with different specializations, it’s your choice.
MULTIPLAYER
Your decisions now impact both your city and your region. Choose to be a good neighbor and send fire and police resources to other cities in need, or specialize in industries that create pollution and then watch as the Sims in your neighbors’ cities become sick. You can also choose to collaborate or compete with friends to build great works or earn achievements by topping the leaderboards. As a live service, the game can simulate real time updates from new challenges to new features and content.
Game Trailer: http://www.youtube.com/watch?v=glee62dKv0c