The Legend of Zelda is a pretty popular little 8-bit beast. One fan, a modder identified as Exkodius, wondered what it would be like to trundle around Hyrule in pixelacious 3D. Like you do. Heeding the warnings, they did not go alone, enlisting the help of a friend to recreate the game in the Doom engine. The friend turned out to not be very helpful and Exkodius spent three years toiling on the dream, creating a fairly faithful 3D rendition of part of the game.
Now, Exkodius is releasing the files in the hope that someone can continue their quest after realising they neither have the time nor sufficient knowledge to complete what they started. “I really hope someone with the passion or just the know how can have some use of this and mabye [sic] even finish it?” Exkodius notes on the Moddb page for the project.
So, if you were looking for a new project in 2019 after that whole “exercise more” thing fell through, you can find all the files and information you need at the Moddb page for The Legend of Zelda: Total Conversion. I mean, before Nintendo finds out and ruins all the fun.