World of Tanks is in a class by itself -- if you want to play a vehicle-based MMO focused around motorized armor units, there simply isn't another option available. And while there were more than a few jokes at the time of its announcement, successful games with a strong vehicle focus exist already. But the core of a game like this is going to be the vehicles themselves, both their diversity and their interesting traits to set each one apart from its peers. The developers have released the access trees for all three main nations in the game -- Germany, the USA, and the USSR -- giving hopeful players an idea of what they can use to thunder about the countryside.
Spanning the period between World War II and the Korean War, the list is fairly exhaustive, showcasing the diversity of tanks on the battlefield. The German progression path even includes the Maus, an experimental tank of absurd size that should please fans of bizarre WWII machinery. And if rolling around in a two-story tank doesn't get you excited, well, you're probably not the target audience. All three progress charts can be found on the official site for World of Tanks.