For several weeks the invaders have been building up their forces on the coast, while the mighty Luftwaffe have pounded the RAF into submission. As the invasion force prepares to strike north and capture London, King Edward VIII refuses the resignation of British Prime Minister Lord Halifax, triggering a constitutional crisis. It is Britain's darkest hour.
Parliament is recalled, and with all the members of both houses meeting in Westminster, a small group of backbench MPs and their families - designated survivors - are taken to a secure location south of the river Thames. They are completely unaware of the imminent events that will thrust them into the limelight, and put the fate of the nation in their hands.
You are among those designated survivors. Your decisions will shape the course of history. Can you save the British people from the invading forces, or will the war be over by Christmas?