Assassin's Creed Odyssey.
The very first moral choice you get to make is wether to kill a sick family that isn't recovering. They looked fine and they said they were getting better, so I killed their would be killers and they were free. Turns out they were sick with the Plague of Athens. Now the intro Island is covered in a eerily thick fog with dead bodies littering the towns and villages. Perpetual rain as well. I could have stopped the Plague of Athens from spreading, now it will effect the rest of the games regions by end game.