It seems like the secret ending in Metal Gear Solid V was unlocked recently for PC players and Konami is currently investigating on what triggered it.
The disarmament ending is a cutscene that triggers only if all players dismantle all their nukes in each of their Mother Bases. Once the nuke count for the whole platform hits zero a cutscene will play, with Big Boss and his men announcing that the world is finally nuke-free. This is considered a near-impossible task for online players and Konami has confirmed via Twitter that the ending was triggered when the nuke count hadn't reached zero.
In Reddit, MGSV players are left frustrated since they've been working on triggering the ending since it was discovered. It was said that around 7,000 nukes were still on the server when the ending was triggered.
Players figured out that this ending existed by going through MGSV's game files and Konami confirmed that it exists and will naturally trigger if players somehow managed to band together. People uploaded the scene anyway right after it was discovered to show a piece of content that, well, thought would never come to light naturally. Have a look below.
What happened? Some could say it might be a little stunt Konami is doing since they do have Metal Gear Survive planned for release this month. A sort of hack to trigger the scene is also a possibility, but right now there no solid reason for the trigger.
It's interesting how players are still working together in achieving this goal of having a nuke-free server. An achievement that I think can only be done in video games. As of this writing, the PS4 version of the game currently has 1,942 nukes, while the Xbox One version has an impressive count of 331 nukes.