Humanity wages war against the Vortex, a highly intelligent alien creature, which invaded the Earth with a robot army and pushed humanity to the brink of extinction using its superior technology and tactical skills.
As a last effort, the Coalition of Independent Nations launched Operation Nightstorm. You take the place of Captain Edward Stalway, a highly-skilled super-soldier, one of the key figures of the operation.
The main objective is getting closer and closer to locating and destroying the Vortex by raiding enemy bases and research stations. By doing so, you get information on enemy activity in the area and gain new technologies, which can be used, to unlock better equipment and weapons.