In Until Dawn, both characters Sam and Mike cannot be killed under any means until the final chapter of the game.

The answer is True because in the game "Until Dawn," the characters Sam and Mike are designed to be essential to the storyline and cannot be killed by the player until the final chapter. Their survival is crucial for progressing through the narrative and reaching the ultimate conclusion of the game. Until the final chapter, the plot heavily relies on their actions and interactions with other characters, making it necessary to keep them alive until that point.