War Thunder is a free to play online 3D airplane simulation game by Gaijin Entertainment for PCs and PlayStation 4. It takes place in World War II, with many historical aerial battles, airplanes and scenarios to play.
It can be played in three modes: arcade for beginners, Historical for real-life scenarios that have happened in WW2, and Simulation. Difference between the latter two is that in Historical, airplane nationalities are locked in depending on the map being played. There are 5 nations with a huge arsenal of airplanes available, they are the following: USA, Germany, Soviet Union, Great Britain and Japan. Each nationís planes are broken into tiers, which must be unlocked by spending research points on them and their different upgrades. This gets quite slow on the later tiers, and there are also premium planes which can only be bought using real money.
Gaijin are also planning to implement tank and naval warfare into this same game, but those are still far away. Currently the tank part is in open beta, with two nations having access to tanks in a separate client.
The game has top-notch graphics and sounds, and an excellent simulation mode that is on par with the best paid simulator PC games out there. If you love World War II and/or airplane battles in general, give this game a try.