World of Tanks
Copied from their website
"World of Tanks is a team-based massively multiplayer online game dedicated to armored warfare of the mid-20th century. The game gives you a unique opportunity to feel like a real tank commander taking part in a furious armored offensive! The game features various types of battles, which allows you either to fight against random opponents of your skill level, or form teams and prove your worth in combat against other teams, or train together with your friends, sharpening various combat skills. All battles are staged on diverse detailed battlefields which offer not only an impressive spectacle, but also the tactical challenge of a variety of battle conditions. You start your tank career in World of Tanks with a selection of three basic vehicles of each nation (Germany, USA or USSR) at your disposal. Select a tank, choose a desired battle type and roll out! Your main goal is to receive as much experience and credits in battles as possible. Use credits to repair your vehicles and resupply ammunition, and to enhance your vehicle?s performance on the battlefield by mounting various additional equipment and consumables or training the crew members of your tanks.
Use experience to advance in the game by researching and upgrading your tanks and modules and unlocking more sophisticated vehicles. Thanks to an advanced system of vehicle upgrade and development you have the possibility to try out virtually all the vehicles and weapons featured in the game! The enormous tank fleet at your disposal features 150 American, German and Soviet historically authentic, light, medium and heavy tanks, as well as SPGs and Tank Destroyers, including both legendary tanks and experimental prototypes."
It's a FTP game but u can spend money if u really want but it is one of the few I've seen that don't actually break the game in the paying peoples favor. All they get is slightly more in game money and exp per battle, so they just advance little faster.
