Various pieces of evidence have appeared over the years to confirm that Super Mario 64 was originally going to include Luigi as a playable character.
In several interviews, including a 1996 interview translated by shmuplations, Miyamoto went on the record as saying that the character was planned for the game but was eventually taken out due "to memory issues". Then, as part of the so-called Gigaleak in 2020, fans were able to discover the development files for Luigi's model and assemble them to showcase the character to the world for the very first time.
However, to our knowledge, at least, no video footage of Luigi in the game has ever appeared. But that all changed over three weeks ago when a YouTuber called Now In Game Channel published a video of a '90s Japanese variety show on the platform, containing roughly three seconds of the character running around a test area in an N64 demo screen.
The footage came to our attention earlier today thanks to the 64DD and Satellaview preservationist LuigiBlood, who tweeted about the amazing discovery, writing: "Here's your only official footage of multiplayer Super Mario 64 from a Spaceworld 95 video kiosk as the camera clearly focuses on both characters". LuigiBlood didn't seem to know what he had stumbled across at first (or was being coy about what he'd found) but went on to emphasize in a set of follow-up tweets that the footage wasn't showing a second Mario but his brother Luigi instead.
Interestingly, though Luigi was eventually removed from the original version of Super Mario 64, Nintendo EAD didn't give up on getting him into the game, with Miyamoto stating plans to introduce him to the 64DD version of the title in an interview with Famimaga 64 magazine published in 1998 (that the English translator Liz Bushouse kindly translated for us earlier this year). Here's the relevant section of that interview below:
Interviewer: Speaking of Mario, I think a lot of people are curious about what's going on with his little brother.
Miyamoto: Oh, Luigi?! Rest assured, he'll be there. (laugh) Luigi will definitely be in the 64DD version of Mario, but we haven't quite decided yet what we're going to do with him.
Interviewer: There's going to be a 64DD version of Mario?
Miyamoto: Oh, has that not been mentioned?! Yeah, we're making a Mario for the 64DD. And both Luigi and Mario are going to be in it. I think Luigi should be able to be used in one way or another.
As history tells us, though, Super Mario 64DD was never released, and instead fans had to wait until the launch of Super Mario 64 DS in 2004 to play as Mario's younger brother.
You can watch the footage in this video. Luigi appears on the second monitor around 13:21.