From the website http://web.archive.org/web/20100110052915/http://www.tsoa.be/html/titelblad_uk_world_at_war.html :
The "World at War" is another rules set in our card driven color coded hex based series. Although it was one of our first projects, it has taken us nearly two years to finish, since mechanized warfare is quite different from e.g. colonial or ACW. Our main objective was to write a set of rules that would allow a fast, yet as realistic as possible wargame.
In order to keep the actual number of pages as low as possible, we have opted for a system that may be compared with "Lego". You may have a huge pile of Lego blocks at hand, yet to build a house, you will only use the ones you need. In our system, the "unit cards" stand for the Lego blocks: there is a huge choice of different units for each nation, yet you will only need those you have units for in the game.
The number of COMMAND CARDS is similar to the other games. So far, we have finished the D-Day to Berlin units for Germany and the USA.