Zelda: The Missing Link is a fan-made Ocarina of Time sequel
With a Harry Potter item mechanic.
Everyone knows Majora's Mask is a sequel to Ocarina of Time - but what happened between the two games? The fan-made Zelda: The Missing Link stitches the two stories together, via a short game created within Ocarina's engine (thanks, Kotaku).
Several new items pop up - the most interesting of which is a Magic Hourglass (no, nothing to do with the Phantom one). It lets Link travel back in time by 10 seconds to solve puzzles, which all sounds very Prisoner of Azkaban.
Really, what it does is track Link's position and move him back where he was standing 10 seconds beforehand. This means you could leap down to hit a switch without anyway of getting back up - except via time travel to where you were previously standing, the door now open.
Is that time travel? Or more like a TARDIS? I'm not sure.
Either way, a lot of love has clearly been poured into this project, from all the dialogue and new music, to small touches such as a more brown-looking Kokiri Forest (because this is set after the demise of the Deku Tree).
It's all the work of the talented modder Kaze Emanuar and a small team. You can watch him play through it in the video below.