The doorway leads to a strange land, where impossible objects exist. Space and time do not seem to behave in the familiar ways here. Exploring this new environment, the player finds several other mysterious doors, each of which leads to another chapter in the history of nuclear weaponry. After visiting test sites (including ones in Siberia, Nevada, and the Eniwetok Atoll) and Nagasaki just before each device is detonated, the player has one scenario left to deal with. The final door leads to the New Mexico desert on July 16, 1945, mere minutes before the test-firing that will change the course of history. But something is wrong at the "Trinity" site, and without the player's intervention things will go horribly awry.