I don't know if Penumbra would fit the killer game definition.
As far as I know, this only refers to games containing "acts of violence, or coonotations to acts of violence, carried out by the player on human, or human-like characters".
You know, like in chess, if you really think about it. These Bavarian madmen are almost scarier than the Rock Worms...
So as long as the people responsible for this kind of accusation don't really play the whole game, which I doubt they would, Penumbra is safe. Part one, at least.