On June 30th, 1908 a mysterious explosion took place over the Tunguska River in Siberia, Russia that wiped out trees and wildlife for over 800 square miles. To this day it remains the largest “impact event” in our planet’s recorded history.
In the years that followed, dozens of scientific expeditions to the site attempted to explain the disaster but failed to come to any conclusions. In the mid-1940s however, a team of scientists from the Russian secret service visiting the site stumbled upon the wreckage of an alien spacecraft containing technology that far exceeded our own. In the years that followed, the KGB set to work harnessing this mysterious new power source and created a new secret weapons program - The Division of Advanced Weaponry or "O.S.O."
They thought they could control the new power they’d discovered, but it began to do more than run their machines. It began to drive the men working on it mad. The man in charge of the O.S.O., General Yuri Petrakoff, seemed particularly affected and on April 14th, 1949, Petrakoff launched a full scale assault on Europe.
One of Petrakoff’s lead engineers, Jesper Teterev, went AWOL and left the program early, wary of what was happening there. He went to live in secret with his sister, Isabel and niece, Allison. While in hiding however, Jesper (with the help of budding engineer and pilot, Allison) was busy building his own mechanized war machine, called the XP-41, certain it may be needed one day to stave off the O.S.O.'s evil creations. Jesper was right.
Source: The Game Website.