https://www.gamespot.com/articles/heres-super-mario-64-but-in-first-person/1100-6455879/

Have you ever wondered what Super Mario 64 would look like from a first-person perspective? Modder Kaze Emanuar released a ROM hack called "First Person Mario 64" recently, and as you can see in the video below (via Kotaku), it changes the way the game looks in serious, significant, and scary ways. It's not perfect, with some of the game geometry breaking in places, but this makes sense considering the designers never intended for the iconic platforming game to be played this way.

The first-person perspective also gives Super Mario 64 more of a feeling of danger and intensity, in particular at the end in the boss battle against Bowser. He looks even bigger and more imposing than ever.