Actually I think this game undersells the full horror of the Slithers because we don't actually get to know any of the victims they pose as. We've never met Monica or Volkhard or Tomas or Cornelia, so we can only guess at what they were like before someone else stole their face. It's hard to get too excited over "this guy I barely know turned out to be some other guy actually."
Imagine if Monica, the real Monica, were a required unit in your class from the start. Imagine if you spent several chapters getting to know this girl before she vanishes one day, only to come back seemingly unharmed but just a little bit different. Imagine Kronya's reveal coming not just with the shock of this strange person who's been in disguise in your midst all along, but with the horror of knowing that the little girl in your class must have been dead for a long time. That all the relief everyone felt when she was "rescued" was meaningless.
Imagine the dread of realizing that anybody you know could go this way, that any face you see might be a false one.
Imagine if every time you let a unit die, there was a chance that someone who looked just like them might appear in the enemy ranks in the future.
