From the review:
"Killing Floor is strong enough to stand on the strength of its gameplay mechanics and the wave-after-wave structure. One could fantasize the "What if...?" of a Killing Floor utilizing the features of the Frostbyte 2.0 engine (or anything approaching modern), but that would probably limit the reach of the game and therefore the audience. With no sign of slowing down, Killing Floor is still worth checking out even three years after it's official release."