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.