Call of Duty: World at War will feature a more mature theme than previous installments in the series. Swimming elements will be introduced to the series for the first time in single player and multiplayer. While in water, the player cannot sprint and will only move at half speed. Flamethrowers, first introduced in Call of Duty: United Offensive, will be reintroduced with new flammable environments. The game will be slightly more open-ended than previous games in the series, as there will be multiple ways to complete missions.

World at War will feature cooperative gameplay with up to four players via split-screen on consoles, or four players online, for the first time in the franchise. Cooperative multiplayer on the Wii will allow for multiple players to play on one screen. It will also use a perk system similar to Infinity Ward's Call of Duty 4. Activision has also confirmed the presence of vehicles in multiplayer.