It's only fair, since Golden Souls 3 turned Doom into a delightful Mario 64-inspired platformer, that now Mario 64 has been turned into Doom. This mod takes the Mario 64 PC port and asks, what if we got a lot of Doom textures and put E1M1 in there? The boos have been reskinned as cacodemons, Mario's rocking Doomguy's outfit and collecting skulls instead of coins, and the music is just perfect.
This mod is a work-in-progress by p3st gaming (whose latest video has a link in the description), and incorporates a Doom HUD credited to DorfDork, KiritoDev, Tilly, Boofster, and cjaawesome. It's on version 0.34 right now, so there's more to come.
Nintendo have taken action against the Mario 64 PC port, but copies of it obviously remain in circulation.