Daniel Smith got the idea of creating a new storyline after he completed the Apocalypse storyline and played "Homefront", a first-person shooter game. Smith has announced that he enjoys studying about space, and while he was playing "Homefront" he replaced 'Home' with 'Space', thus creating "Spacefront".
The storyline of Spacefront starts out following an alternate storyline on Call of Duty: Modern Warfare 2, but it soon becomes non-related. It uses characters and some weapons from Modern Warfare 2 also.
The storyline consists of four chapters and one DLC map pack (Wastelands).
Chapter 1: Earth
Chapter 2: Ascension
Chapter 3: Space-struck
Chapter 4: Final Fronts