So, they're new, nobody could see that coming, they're terrifying, seemingly unstoppable, and the first few times you see them odds are very high you're going to be reduced to running from the wreckage of your formerly-comfy "base" chased by half the entire zombie horde, until some week in your desperation you finally try something that happens to have at least _some_ effect on them and start piecing together some workable defense tactics. Assuming you live that long, of course.
That description would make me want to play that game.