You are not limited to any particular decade. Out of all the point-and-click adventures you have ever played on anything ever, what puzzle was the best of the best? What puzzle stands out in your memory as zomg-that-puzzle?
I’ll kick it off with my most memorable:
Game: Riven (Myst II)
Puzzle Location: Main Dome Island
Puzzle Objective: Map the locations of all spinning domes in the world of Riven.
The map grid puzzle on the Main Dome Island is one of the most genius but complicated puzzles I can remember doing in a point-and-click. For those who never had the pleasure, the world of Riven consists of several islands that you hop around via little roller coaster cars (video). Each of the islands has a spinning golden dome on it, which you can get inside of by hacking a sort of password puzzle. Once inside, there is a sort of viewfinder puzzle (screenshot) that reveals to you a symbol. It’s not immediately clear what the significance of the symbol is early in the game. And that’s all the spinning domes do!
Later, when you reach the Plateau Island, there is a complicated map room that lets you view elevations (screenshot) of all the islands, and the geography makes it clear where the spinning domes on all the islands are located. Using those elevations, you pinpoint the coordinates of the spinning domes on the map grid and write them down. Like, on actual paper. (No in-game quest journals!) Then there is another secret underwater room on the island with a special chair (screenshot) that, when you press buttons on it, associates colors with symbols. The symbols are the ones you found in the spinning domes, so this lets you associate a color with each of the spinning domes.
You then take ALL OF THAT information back to the Main Dome Island, where there is a huge grid inside the main dome. Next to the grid are a bunch of colored marbles. You have to use the coordinates you found and the color associations you found to place the colored marbles (solution) on the 625-square grid to accurately map the exact locations of all the spinning domes in the entire world of Riven. Even then, you find out that some of the information is missing and literally impossible to find, so one color and one marble location have to be figured out purely by deduction.