FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Consequences for Immersion and Storytelling
Saving a game is not always beneficial to the player's experience. The act of saving a game takes place outside the game world and, as a consequence, saving harms the player's immersion. If a game tries to create the illusion that the player inhabits a fantasy world, the act of saving destroys the illusion. One of the most significant characteristics of real life is that you cannot return to the past to correct your errors; the moment you allow a player to repeat the past, you acknowledge the unreality of the game world.
The essence of a story is dramatic tension, and dramatic tension requires that something be at stake. Reloading a game with a branching storyline affects the player's experience of the story because if he can alter the future by returning to the past and making a different decision, nothing really hangs in the balance. Real-world decisions bring permanent consequences; you can modify some in the future, but the original decision cannot be unmade. But when a player follows first one branch of a branching storyline and then goes back in time and follows another branch, he experiences the story in an unnatural way. The consequences of his actions lose their meaning, and his sense of dramatic tension is either reduced or destroyed completely. What is a benefit to strategic games—the chance to try alternate strategies—presents problems for storytelling.
Nevertheless, the arguments for saving outweigh these disadvantages. If the player destroys his immersion by repeatedly reloading the game, that is his choice and not the fault of the game designer or the story. As Chapter 7, "Storytelling and Narrative," pointed out, a weakness of branching storylines is that they require the player to play the game again if he wants to see plot lines that he missed on his first play - through. Allowing the player to save and reload makes that easier for him. He may always choose not to reload if he doesn't want to.