Greek Mythology is just the starting area. Many other world mythologies after that.
Can't tell much, sounds like gathering stones of power is the big excitement focus. You do level up. Microtransaction store will sell you xp multipliers for real world money, maybe other good stuff. Couldn't tell much more.
Petroglyph was started by old Westwood Studios people. http://en.wikipedia.org/wiki/Petroglyph_Games
I tried and tried to like Age of Mythology from the now sadly deceased Ensemble Studios. But it was always a bit too tedious for me.