The biggest problem with C.O.R.E. isn't that it borrows its elements from older games in the genre; it's that these features are not implemented well. From arduous level design to lame enemy encounters, the single-player campaign is more inclined to frustrate than to thrill. The multiplayer is slightly better, but the claustrophobic stages remove much of the strategy of combat, and the clunky controls become painful before long. This aggravating, generic shooter is not worth your time.