G4: "Not counting the Atlantian hub area you reach in the second chapter, the majority of the game is traditionally linear for a first person shooter. That said, the levels are definitely not straight lines.
This is best exemplified in the Siberian level, an area that features mountainside caves, outposts with inconveniently placed ladders, and bases placed on cliff walls. The only real break from the linearity is in a brief section in China where you need to investigate multiple adjacent rooms in order to progress. While the overall journey didn’t feel especially original, I certainly wasn’t bored. It does help that the game throws it share of curveballs, mostly in the form of unexpectedly large waves of enemies from time to time."