On PC:
Wizardry IV: The Return of Werdna. I dare anyone who hasn't played any game of the series to get out of the very first 2x2 room without googling it. It was so notoriously difficult that the later editions of the game came with a sealed letter to that specific puzzle, and it goes rapidly downhill from there
On Consoles:
Either Zelda II: The Adventure of Link or Super Ghouls 'n Ghosts
On Handhelds:
Gargoyle's Quest
Never beat any of the mentioned games, although I didn't play much of Super Ghouls 'n Ghosts and I reached the last Boss before Shadow Link (but without enough magic to cast Lightning) in Zelda II







