The game is based around combined arms battles on air, land, and sea with vehicles from the Spanish Civil War to the Cold War period with an emphasis on World War II. Players have access to more than 800 playable aircraft, tanks, and ships from the Soviet Union, Germany, the United Kingdom, the Japanese Empire, the United States, Italy, and China (only on the Chinese server). Other nations, such as France, Canada, Australia, and Romania, are also featured as part of the arsenal of the six main nations.
Most in-game maps are either directly or indirectly based on real battles of the era such as in Stalingrad, Russia, or Peleliu, an island in the Palau chain, though there are exceptions.
War Thunder is divided into three main game modes, which define the overall realism behind the performance of vehicles in battle; the amount of assistance provided to the player (e.g. through the interface); and the type of maps and missions played. Players may choose to participate in a battle with joint ground forces and air forces in tank battles or to choose to operate air vehicles only in air battles.
In this mode, the game draws two teams of players (of up to 16 players on each side) with vehicles from different nations of similar combat performance. It is possible to see vehicles of the same type on different teams, and different countries on the player's own team. Damage and physics are greatly simplified (e.g. in very high speed dives planes do not have their wings ripped off and are still controllable, ground vehicles receive a boost in engine power), but retain some realism (e.g. bombers are not as maneuverable as fighters, aircraft have limited ammunition available but are able to reload midair).
For aircraft, games are played in either "Ground Strike," where in order to win players must destroy all enemy ground units, shoot down all enemy aircraft, destroy the enemy airfield and bombing points, "Domination", which consists of seizing enemy airfields by touching down on them for about five seconds, causing the enemy team to lose points, or "Air Domination", which requires players to have total control over an area of airspace for long enough to capture it. Also, to help simplify aiming, a 'leading marker' appears when an enemy plane is in range. This shows a prediction of where the enemy plane will be by the time the bullets of the smaller calibre weapon arrive if the plane continues its current trajectory, greatly improving user accuracy.
For ground forces, "Domination" revolves around the capture of three strategic zones on the map, with "Capture" featuring only one. In "Break", the two teams must capture a series of points in order, while in "Battle", each team has its own base zone and must prevent it from being captured. Similarly to how aircraft have a "leading marker", ground forces have a reactive crosshair that factors the ballistic drop of the vehicle's primary weapon at range. It's also color-coded to indicate whether the vehicle the player is targeting can be penetrated by the ammunition they are using at the range they're sighted for, or whether they're targeting an enemy or allied vehicle.
Previously called "Historical Battles," this mode is designed for more advanced players and offers realistic physics and damage modelling while retaining some of the interface and control simplifications of Arcade.
In air battles, Fighters will have to takeoff from the airfield. Interceptors will start airborne. Attackers will also start airborne but higher than Interceptors. Bombers will start about 2,000 metres (6,600 ft) off the ground. More realistic damage models makes long-range "sniping" difficult, and there is no 'leading marker' to assist with aiming. Also, due to realistic G-forces, making tight maneuvers at high speeds can cause pilots to black out or their planes to rip apart, and the views available are the same as in Arcade Battles. Once ammunition is used up, players will have to return to their airfield to reload and repair. For the majority of matches in this mode, players are selected to have only one nation per team, making it possible to recreate a real scenario, such as the Battle of Stalingrad between the Soviet Union and the Third Reich.
This mode is located in the events section, was called "Full Real Battles" and was based on Realistic Battles with more restrictions on the user interface and controls; only the first-person view (in the cockpit) and external turret gunner views for aircraft are allowed in flight, while tank players are restricted to the gunner's scope, the driver's port or Cabin (truck), or a commander's perspective located above the vehicle. Additionally, aircraft can only be played in "Full Real controls" (there is no 'instructor' to prevent the aircraft stalling and the mouse can only be used to simulate a joystick). Players retain the option to have flaps, trim and engines automatically controlled in Simulator mode. The Heads Up Display is available to display speed, altitude, heading, engine/throttle settings, oil and water temperatures and basic vehicle damage status.
No player tags are given for the enemy team and friendly player and AI-controlled entity tags are only provided for aircraft within 0.9 kilometres (0.56 mi). Thus, players must pay particular attention when dealing with specific aircraft and tank types that are available to multiple nations and vehicles that can use different roundels other than their own default through personal customization