It is a pay to play gane
The game battle supremacy is dashed on tanks but you can drive planes and warboats in there campaign!
Plus check the amount of players who actually play that game, phisics are horrible, planes move like WWI planes and over that, is horrendosly hard to get to better tanks/planes, which forces you to pay over the $4.00 you pay for the game.
Campaing? it is short as crap, and when you actually play multiplayer, you rarely see people play. Why? because no one wants to pay $4.00 on a game that never gets updated, neither have any concideration on making the game free to play.