A secret from 1994’s Doom II, hidden for so long that its trigger was assumed to be a bug, has finally been discovered.
Via RPS it’s on Map 15, and involved a teleporter that would display as being a secret, but would never actually trigger. That’s because it couldn’t be set off by the player simply standing on it: a workaround had to be discovered.
One that Zero Masterfound was…letting an enemy knock you onto it. Here’s co-creator John Romero with the congratulations (and details):
Secret explained: A secret teleporter is marked as a discoverable "secret", but when you touch it, you never enter the sector. So you would never get inside the teleporter sector to trigger the secret. The only way to trigger this secret is to be pushed by an enemy into it! #doom
— John Romero 🤘🏽 (@romero) August 31, 2018
Saying he just needed to be knocked onto it is actually under-selling it a little. To activate the teleporter, Zero Master has to lure a Pain Elemental into giving him a nudge after a lengthy and very close-range game of cat-and-mouse. You can see the pursuit in this clip (from around 1:45 onwards).