Giles Goddard, from the late 80s to the early 2000s, was a key talent behind-the-scenes for Nintendo. When the Nintendo 64 technology came around, Goddard was tasked with developing various prototypes to show what the machine could do: the most well-known of which is undoubtedly Mario's interactive face at the start of Super Mario 64. Turns out there was something even more eyebrow-raising in the works: a Zelda prototype that, well, was basically Portal before Portal.
"I found an old directory of source code I'd mocked up, and it was the first map of N64 Zelda with the castle [...] I was doing all these experiments, you could have a portal, look through, go in, and then you get teleported to a different part of the map," said Goddard. "You’d see through a door to a different part of the map, walk through it, then walk back through it if you see what you mean."
"It was R&D for the game basically, what could we do with the hardware of the N64, this was basically a demo of portals, actual portals you could see through to other parts of the map."
The prototype didn't have an equivalent to the portal gun, with players instead spinning crystals to see through to different angles of the world, and then step through.
Some of Goddard's work on Zelda did appear in public: at the time, the demo shown at Nintendo's 1995 Shoshinkai (trade show) had young fans like me wetting their pants in anticipation. Ocarina wouldn't bear much resemblance to this in the end, and it's easy to see why a prototype concept like the portals would have been a tough fit: though Goddard reckons the reason is much simpler. "They probably never saw it."
Portal began life as the indie game Narbacular Drop in 2005, before Valve employed the entire team to have another go at the concept: Portal released in 2007, and we've never been safe from cake memes since.
"Yeah when I saw Portal I thought oh actually I had that running on the N64, I should've released it then," laughs Goddard. He says he's still got the working prototype in the offices but, as it's Nintendo's property, we may not see it for a long time: if ever.