It could be a horror-themed adventure game. Maybe the guy is driven by extreme fear or a dark motive in that creepy setting.
It could be a survival adventure game where the guy had to kill someone in the bathroom to protect himself or to gain an important advantage in a dangerous situation.
This might be a mystery-solving adventure game. The killing in the bathroom could be part of a complex puzzle for the player to unravel and figure out the truth behind it.