According to his Xbox, one player just managed to complete Fallout 4 without even setting foot outside of Vault 111 (spoiler alert: he definitely left Vault 111).

User TheJFG4 posted yesterday on the Fallout 4 subreddit that he has unlocked 83 of 84 achievements in the Xbox version of FO4. The last achievement he hasn’t unlocked yet is probably the very first one any other player would unlock in their first 30 minutes with the game: the “War Never Changes” achievement.

You unlock War Never Changes by entering The Wasteland, as per the achievement’s description. This means you simply need to leave Vault 111, the vault your protagonist is in during the opening section of the game.

So how is this possible? Well, in classic Bethesda fashion, it’s because of a bug.

However, it might be a bit harsh to blame Bethesda here, as the error probably lies with the Xbox One’s Quick Resume feature – and not with Fallout 4.

TheJFG4 actually left Vault 111. That was pretty much the only way to unlock the other 83 achievements, especially on Xbox systems where it’s much harder to unlock achievements by cheating (as opposed to, say, PC where it’s ridiculously easy).

In fact, this seems to have happened: TheJFG4 completed all of Fallout 4’s achievements in one playthrough, but the very first achievement unlocked had a bug and never triggered due to the Quick Resume feature.

As many other players noted in the thread, this happens a lot with Xbox achievements. One player noted, “I assume this has something to do with Quick Resume. Never use Quick Resume if you care about achievements. It messed up my completion of the Arkham games…”

So unfortunately it’s not really possible to legally complete the game without leaving Vault 11, but hey – at least TheJFG4 can fool others into thinking it’s possible.