Originality debates have been thrown around back and fourth for decades. We need to face it: We are in a day and age where being original in games is either unusual, or a hit-or-miss affair. Being original is a very risky task, and anyone that attempts it is usually met with failure, despite praises to the contrary. We enjoy more of the same no matter how many times we demand originality. We always go back to more of the same.
Most game concepts, ideas, and plots, are all used at one point or another. While yes, the game may be different and neat; it is rarely original. Looking at a newer game like Left4dead. Is it a nice change of pace from zombie games? Sure.
Is it original? No.