Best Puzzle..

My quest for the scariest game has brought me to many different puzzles with in various video games. Recently, while plpaying through the original Silent Hill, I encountered one o fthe most difficult puzzles I have ever seen in a video game. The (piano puzzle in the school, like WTF??) What are some of the hardest puzzles you've ever seen in a videogame?
7th guest, spill the blood on the rug lol..
Some of the later ones in Treasure's "Light Crusader" were pretty tricky. I don't remember any specifics, but i do know that i was stuck for lengthy amounts of time on alot of them.