Gating
Many games
prevent players from progressing using gates. A gate might a physical door that they have to unlock, a time window that they have to show up for, a specific condition like a solving one task before unlocking another, or a requirement that a player research one technology before being allowed another.
http://www.whatgamesare.com/gating.html
Gating in level design
‘Gating’ describes a method in game & level design for creating linear paths through what would outwardly appear to be non-linear worlds. The Zelda series is basically a master class in this technique. While providing you with a world you can explore at your leisure, important plot areas and stages of progression are always
blocked off until you arrive at them when the game wants you to. Often by acquiring a skill or item that allows you to pass the previously impassable.
Often a game will do this by gently leading you down a path that seems to reach a dead end, a huge boulder
blocking your path. (Dodongo’s Cavern in Zelda: Ocarina of Time) At this point the game might give some subtle reference to how you might bypass the obstacle, with varying levels of explicitness. “Oh if only we had some kind of explosive!”.
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