In another thread @IanForce made this suggestion:
“Someone should consider making this an alternative entry into the story. Remember Half-Life? After the initial installment, we had Opposing Forces (military) and Blueshift (police). It could start out as single-player and eventually develop into co-op as the different protagonists are brought together (e.g. by missions).”
My thoughts are that is a REALLY great idea. An alternative storyline from the POV of a policeman or a soldier would give the whole game a fresh new aspect. Maybe a civilian who is a member of the organisation for safeguarding the population. Or… maybe even a sinister G-Man who is behind the machine problem. Or… one of the scientists who survived the assassinations. There are so many ways one can look at the structure of the game’s story and events through fresh eyes.