"The goal of a game is to deliver entertaining content to players as smoothly as possible."
This basic assumption underlies everything about a certain philosophy, and it has some insidious implications if left unexamined.
I define content as everything that the player can experience. There's two types. You interact with Gameplay content in order to achieve one of multiple outcomes. Based on that outcome, you unlock Reward content. This includes mechanics (A new spell, a shotgun), narrative (a cutscene), and art and sound (the enemy explodes in slow-motion with a satisfying "SPLURCH"). Content is entertaining if the player wants to keep experiencing it.
A game designer's job is to make sure the player experiences as much entertaining content as possible, and as little unsatisfying content as possible. To ensure this, content should be delivered smoothly, to make sure that the player is motivated to keep consuming it. Game designers strive to eliminate downtime, backtracking, and filler content. Losing is generally not entertaining content, so save systems minimize death and repetition. The game should be carefully designed to make sure no-one gets frustrated, lost, or confused, carefully guiding the player through either direct orders, physical walls, or subtle environmental cues. The ideal is that every playe experiences every piece of entertaining content. Addictiveness is the holy grail.
The direct effect of this theory: Everything is made for you.
Obviously, the goal of almost every work in every medium is to make the audience glad they experienced it. The difference that comes with games is that the audience is also the protagonist. In a movie, comic, book or play, everything is made for a third party watching in fromthe outside. In a game, everything is made for the main character.
Everything you (the main character) can possibly do is content. That means everything you can do will be fun and rewarding, and you should do as much of it as you can. There are no secrets you're better off not knowing. No relationship will ever be bad for you. There's no enemy that you shouldn't attack, no place you shouldn't go to, no goal that isn't worth achieving. You should kill every enemy, fuck anyone who's available, talk to anyone who'll talk back, make every promise they'll let you make and pick up everything they own when their back is turned. All these things are content, and the purpose of content is to be consumed and reward you for consuming it.
They tell her it's a long and arduous journey up to the peak. She knows that the journey was tailor-made to offer a smooth, enjoyable experience to someone with her exact abilities. If she doesn't have a jump button, there will never be a need to jump. If getting up the mountain was long and arduous, the game would have failed to smoothly deliver content.
The villagers wail that all who enter come back broken and twisted. Geraldine knows that everything in the world exists to reward her personally. If she can enter Death Mountain, then it must be gameplay content, which means that she'll be rewarded for completing it. Including something that didn't exist to entertain and reward the player would be bad game design.
Thus, game designers must constantly bar your way with their left hand while waving "Come hither" with the right. The left hand tells you that the way is dangerous, that this enemy is too terrible to fight, that you're a crazy maverick who's breaking all the rules. The right hand reassures you that you're actually doing the right thing. That enemy was made to be killed by you. This is the way you're meant to go. Keep going, you'll be fine - nothing can actually hurt you.*
*A piece of directors commentary on Half Life 2 muses on how hard it was to convince players to drive through a bunch of "KEEP OUT" signs on the side of a cliff.