You've seen it a million times, in puzzle books, video games, or even children's toys, and you've probably solved it a million times. You may have even made one if you've taken a computer programming course. It's the humble StockPuzzle, a boon to anybody who can't be bothered to come up with an original puzzle. At least one of these puzzles always seem to pop up in situations where OnlySmartPeopleMayPass.
In adventure games, a StockPuzzle is nearly always a SetPiecePuzzle. The reverse is not true: A SetPiecePuzzle can be original, and in order for a game to be enjoyable at all, it had better have some original puzzles.
These sometimes pop up in other media besides video games, usually in programs that are partly or wholly edutainment. You have to wonder whether it's GenreBlindness that keeps people from knowing the solutions to these puzzles in advance.
Not to be confused with a StockVideoGamePuzzle, which is ''necessarily'' a video game puzzle; a StockPuzzle can be reasonably implemented with pen-and-paper or a physical toy, and will often date back at least several decades or even centuries.