Made by: Nival, a Russian studio best known for Heroes of Might and Magic V
Releasing: Spring 2013 (North American version—the Russian client has been running in open beta since last year.)
What's different about it?
A lot of what makes Prime World different takes place outside the match. You'll have a persistent city along the lines of Age of Empires 3 and Age of Empires Online, featuring buildings that generate resources which can be used to buy things. The skill system is also very different—for each hero, you'll create a build out of a few set, character-specific skills, and an open-ended pool of dozens and dozens of common skills that you'll accumulate through game currency and real money transactions, much like a collectible card game.
Prime World has also gained attention for the fact that it uses Facebook integration to determine whether you are male or female, and flags your account accordingly. You'll have a discount on characters of the same gender you listed, and there are mechanics in matches that make it beneficial for two opposite-gender heroes to fight together. The developers say these features are popular in the Russian market, but may be removed if the English-speaking community objects to them strongly.
Can I play it?
The English/North American version is currently in closed beta, which you can sign up for here .