From the web-site description:
"It is the year 1940. France has surrendered. The British and the remains of the French Army have retreated across the English Channel. Germany now controls the whole of Western Europe. The United Kingdom stands alone, waiting for the Germans to strike. Hitler approves plans for an upcoming invasion of the United Kingdom. A plan called Operation: SEALION. The invasion of the United Kingdom is about to begin!"
This follows in the same vein as some other 'Battle' GAME based upon the "Axis & Allies" series, while you'll need to procure the necessary 'bits' from one of those to play this. There are entirely NEW components made up for this, with "Order of Battle" charts, the 'Gamemap', and with '3' SETs(or 'kinds') of CARDs for use in it.