Play Super Mario 64 on an emulator? Never fear, we've got ponies for that.
The Super Mario 64 Texture Pack is at it's best inside Peach's castle. The walls are painted with a bright Equestrian landscape, the floor bears Celestia's seal, and stained glass Nightmare Moon and Celestia replace the original circular window. In-level, apple trees are visible and the ground textures have changed somewhat, but the feel of the game has changed little. Still, it's entirely worth a try!
Trailer and installation instructions after the break!
The thing that would really complete this mod is to sub out Mario for Twilight Sparkle (admittedly, a trickier task than textures.) Then, someone should get on making me a ponified Luigi's Mansion starring Fluttershy. Pretty please?
The description of the trailer above links to a video with full instructions for adding texture packs to Nintendo 64 ROMs. In case you wanted an abbreviated version, I've copied the gist of it below:
1. Make sure you have a working Super Mario 64 ROM running on the Project 64 emulator. If you've never used an emulator to play games before, make sure you have this working first.
2. Download and install Rice's Video Plugin. When it asks you to choose install location, make sure to give it the directory in which you've put Project64.exe. (Something like C:\foo\stuff\Project 64).
3. Open Project 64, go to Options>Settings>Plugins and select "Mudlord's Rice Video Build 6.1.4" as your Video plugin.
4. In Project 64, go to Options>Configure Graphics Plugins>Texture Enhancement and make sure "load hi-res textures if available" is checked.
5. Download the Texture pack and copy the folder "hires_texture" into "Project 64/Plugin."