Based on the award-winning Advanced Third Reich/Empire of the Rising Sun gaming system, A World at War features a dozen global campaigns and regional scenarios ranging from the introductory Battle of the Atlantic and Barbarossa up to separate European and Pacific campaigns.

The second edition of A World at War adds clarifications and refinements based on thousands of games played since 2003, based on contributions from hundreds of A World at War players (the A World at War Yahoo discussion list alone had recorded nearly 60,000 posts since A World at War was first published).