The story focuses on the final battles of World War II in the Pacific and Eastern Europe involving the United States, the Empire of Japan, the Soviet Union, and Nazi Germany. It is told from the perspectives of a Marine Raider and a Red Army soldier, and is based on several historical battles, including the Makin Island raid, the Battle of Peleliu, and the Battle of Berlin.
The multiplayer portion of the game contains various game modes, and contains a leveling system that allows the player to unlock additional weapons and rewards as they progress, which was originally implemented in Call of Duty 4: Modern Warfare. A new feature to the Call of Duty series is the co-op mode, which can support up to four players online and two offline.
World at War will feature a more mature theme than previous installments in the series. Swimming will be introduced to the series. While in water, the player cannot sprint and will only move at half speed. Flamethrowers, introduced in Call of Duty: United Offensive, will appear alongside flammable environments. Vehicles (i.e. Tanks) will also be reintroduced in this edition of Call of Duty. The game will be more open-ended than previous games in the series, as there will be multiple ways to complete objectives.