I felt terrified for the first half of the game, the music and atmosphere was just really scary. I was hoping the game would continue after you reach that final square, it would've been a really neat plot twist. Also, loved the narrator. The first time i killed everything (though quickly realized that they couldn't actually do anything to you), The second time i rushed through avoiding all of them and loved seeing the changes in dialog. The third time i killed one and rushed through but the dialogs were mostly the same. Ah, and the switch in music in that last section is a bit abrupt.
Really enjoyed this one (though the music and atmosphere were scarier than the actual contents of the game ;) ). I'd love to see it expanded, perhaps as another exterminator comes and you have to lead your new civilization to safety or something. I'd also like to see the horror aspect developed more!