Or even the original Prey
, remember that. Running on early Nintendo 64
hardware, programmer Giles Goddard (of Star Fox and SuperFX chip fame) was putting together a Hyrule Castle demo that had a crystal that would instantly teleport you to another section via walking through it. Like a portal. Like... Portal
Check it out.
Bear in mind that this is from around 1996, a time when 3D graphics in games were blocky and ran at around 20-fps at the best of times. For those that played what would eventually become The Legend of Zelda: Ocarina of Time, you'll no doubt recall that it didn't have the portal stuff in there -- which didn't make it past the tech-demo stage.
It's impressive, and a nice little slice of videogame history.