Zelda II likely needs an introduction as much as any other Zelda game, not very much at all. This game is notorious for it's difficulty, and boy does it deliver! While most of the game's difficulty stems from it's battling and platforming, it can also be exceedingly difficult to tell what you are suppose to be doing in places as well, and the cryptic, short, mostly useless responses from townsfolk don't help much most of the time.
All that being said, it does feel like an accomplishment beating this game, though I couldn't imagine doing it on a real NES! Without savestates and doing difficult parts over and over I may have quit before I finished.