The fan made PC port of ported several times to PC in the past, and the modding community has often taken the chance to further polish this historic game.
Super Mario 64 has remained a timeless classic in the world of video games. It was remade for the Nintendo DS as Super Mario 64 DS and was a launch title for the system in 2006. The remake featured even more stars to collect in the world, as well as multiple playable characters in the form of Yoshi, Luigi, and Wario. It also featured extra mini-games that were present in New Super Mario Bros. for the DS. The original Super Mario 64 has been ported several times on Nintendo's virtual console systems, most recently with Super Mario 3D All-Stars, but that collection is unfortunately no longer for sale digitally, and physical copies are priced extremely high online.
Super Mario 64 Plus is a modded version of the Super Mario 64 PC port. Made by Mors, this version of Super Mario 64 has a variety of new features, such as updated textures, the ability to remain in a level after collecting a star, and many other new settings. It's also able to run in 60 FPS and has a permadeath mode where if Mario dies once, the player has start a new game from scratch. This is an optional mode players can turn on should they want the ultimate challenge.
The main concern with this type of mod is that Nintendo will likely file a claim towards it. Nintendo has quite infamously taken down Super Mario 64 PC ports in the past. The Mario Fan Games Galaxy Twitter claims that Nintendo tends to take down remakes of existing games rather than original fanmade games, but since this is a modified version of a Nintendo game that at least used to be for sale on the Switch, this is something that could be targeted by Nintendo if it caught the company's attention.
Only time will tell if Nintendo does take it down in the future. For now, the rom is available to now through MFGG.net. It provides an enhanced and unique way to play Nintendo's classic game. It grants all sorts of quality of life changes, new modes, and new textures to give the levels unique designs, putting a new spin on Super Mario 64.