Way back in 2012, Google "released" an 8-bit version of Google Maps as one of the company's then-annual April Fool's Day jokes. There was a low-res 8-bit style of Google Maps to play with, but the company didn't deliver on its promise of a cartridge you could pop in your old Nintendo Entertainment System. Gizmodo noticed that, nine years later, someone has figured out how to pull this off, with the help of a heavily-modified NES system and the previous work of other hackers before him.
Specifically, YouTuber ciciplusplus used a method to build his maps inspired by someone who figured out how to translate Bing Maps aerial imagery into 8-bit tiles that make up scenery in the original The Legend of Zelda NES game. Ciciplusplus used a similar method to convert Google Maps images into what appears to be tiles from the NES game Dragon Warrior (yes, Dragon Quest for those who didn't grow up playing it in the US).
As for the elaborate mods he made to a standard NES, those were inspired by YouTuber TheRasteri, who figured out how to get Doom playing on his NES (of course). You can see a full video of how he pulled it off below:
As for the final Google Maps on NES product, well, you can vaguely make out the shapes of continents, and areas by the coast are recognizable, but once you zoom in, there isn't a whole lot of detail to distinguish what you're looking at. Still, it's an impressive and fun hack that we're guessing Google didn't think anyone would ever pull off.