As an example of one of the more notorious puzzles in the Sierra games of yesteryear, in Space Quest, you have a sand skimmer (think Luke's sand speeder).

When you get to where you are going, you need to sell it for money. If you get out without removing your keys, it is stolen. Then someone offers you enough money to continue on in the game. If you say yes, then much later in the game you die because you don't have a jetpack. If you say no, they offer to throw in their old jetpack. There are literally no hints that a jetpack would be related to selling your skimmer. You just have to reload old saves and try random things until you get one. And hope you have enough saves that you didn't overwrite one from before you sold the skimmer, or you need to start the whole game over.