Super Mario 64 Port is an unofficial version of Super Mario 64. The game originated from a recreation of the Super Mario 64 source code, a result of the Nintendo 64 Decompilation Project.
The game needs to be compiled in order to be played, being like the original game, but with technology enhancements and an all-new coding.
Like a mod, the player still needs to have the original game to have its assets built in the new code (which is important to note, as distributing the compiled game on the web is copyright infringement, but the source code, created from scratch, isn't).
Having a new and understandable code in C, the game can be modded with less effort. A Windows (and Linux) version (with native 4K resolution, 60 FPS, widescreen and XBOX controller support) was released in 2020, gaining popularity and a modding community.