About two-thirds of the way through the game, the pack of sled dogs the characters have brought on their polar expedition must either be put down humanely or left to starve on the ice. The decision is handled seriously and respectfully, but it’s still shooting several dogs.
It can happen during i believe act 3, if (SPOILER) you do not keep up your loyalty with Dr. Nutlee - he will commit suicide by wandering off into the ice, thinking himsellf a burden.
Yes, though optional - there are two occasions in which you can shoot another character, and one occasion where another character shoots at you, though the latter does not result in death.
One character can suffer a fatal heartattack if you decide to ignore the doctors advice and put him back to work despite his illness. Easily avoidable by putting him on rest.
Yes, in one of the two main branches the player character can gain awareness of the game they are in, its endings / its branching nature. The same goes for one other character in the game, who has been aware of this for a long time. They directly address this.
No, but a main character develops what reads as an addiction to a supernatural substance of sorts - not quite drugs, but could still be triggering i suppose?
The player character can be taken into custody, as well as two other characters in the cast. All three can also be marooned and left for death in the ice.