As if Zelda II wasn't hard enough, a fan has remade the game so that it's played through the eyes of Link.
The NES's Zelda II: The Adventure of Link, sequel to The Legend of Zelda, discarded the first title's top-down view and dropped main character Link into a side-scroller. A fan named Michael A. Johnston decided to change the view a second time by converting Zelda II into a first-person shooter. Until you lose a little bit of health anyway, at which point it becomes a first-person poker.
Johnston only remade the game through to the first boss, and changed a few aspects of the game due to time constraints. There are no towns, it doesn't include every enemy, and players don't level-up. You do still run around and poke enemies with a very short sword, so if you play it you'll notice that it definitely feels like Zelda II from a first-person view. If I were Link, I would have invested in a crossbow.
Though the world map looks just like Zelda II's NES version, Johnston's 3D modeling work on the enemies (and on Princess Zelda) looks very nice and fits with the feel of the original game. Johnston says this project is the result of his "learning programming for the first time and a labor of love making this game in 3D." He probably could have picked a more beloved NES game, but hey, he did a nice job nonetheless.
The game can be played through a browser here, and a full walkthrough is included.