G64

A Garry's Mod addon that uses libsm64 to put a playable Mario in the game.

Installation

Download G64 from the workshop. Alternatively, clone this repo in your GarrysMod\garrysmod\addons folder.
Download the G64 binary module and libsm64 release from the releases page.
Obtain a copy of the US version of the Super Mario 64 ROM (MD5: 20b854b239203baf6c961b850a4a51a2, SHA1: 9bef1128717f958171a4afac3ed78ee2bb4e86ce). No, I will not tell you how or where to get this, nor will I send it to you.
Now that you have every file you need, extract the release you downloaded from here into your GarrysMod folder: steamapps\common\GarrysMod.
To check if you did this correctly, check that both GarrysMod\bin\win64\sm64.dll and GarrysMod\garrysmod\lua\bin\gmcl_g64_win64.dll exist.
Open Gmod and load a map. Open the spawn menu and under Utilities > G64, set the path to the ROM you obtained.

You're now all set! Spawn Mario from Entities > G64 and if you did everything right, Mario will spawn. Enjoy!

Source to my gmod fork of libsm64 can be found here: https://github.com/ckosmic/libsm64/tree/gmod
Source to the G64 binary module can be found here: https://github.com/ckosmic/libsm64-gmod

Many features of this addon (like sound and multiplayer) would not be possible without @dylanpdx's Retro64Mod fork of libsm64.
SysTimeTimers by @SnisnotAI
gmod-luabsp by @h3xcat