Trivia: Unwinnable by Design
The apparent intent of filling a game with unwinnable situations was to force players to explore the entire possibility space. By essentially making it impossible to complete the game the first time through, players wouldn't be able to ignore the earlier parts of the game as irrelevant, and would have to keep the puzzles they "know" how to solve in mind in case there was an alternative solution. Ron Gilbert
was instrumental in forcing this trope out of fashion in adventure games - part of his manifesto on adventure game design asserted that the "correct" playthrough should be a logical, linear story, and so characters shouldn't pick up items merely because the player knows a puzzle requires them later.