Aliens have invaded (yet again), so it's your mission to kill them all. And there's a lot of them. It's your standard shooter fare, with little to distinguish from the multitude of other shooters out there. The terrain looks nice in a basic, texture-mapped sort of way, but all the different terrains of the earth, be they jungle, desert, or city, all look remarkably similar. It's only when the FMV pops up that things get interesting, and that's only because the acting is so bad.
Things move along smoothly enough, but the control is so sluggish as to make it almost impossible to actually hit anything. Try Warcraft instead. This one should've been left in the past.