The Diablo games are well known for their callbacks and Easter eggs, going all the way back to the secret Cow Level in Diablo 2. Diablo 4 is no exception to that rule: Some, like the return of the original Diablo music in the game's first act, are obvious and unmissable, but others are much better hidden.
The Hidden Camp is a good example of the latter. The first town that players encounter in act 2 of Diablo 3 has been recreated in Diablo 4, yet somehow it went unnoticed (or at least unreported) until now. But redditor Fearlessmojo ran across it, and shared evidence of his discovery on the Diablo 4 subreddit.
The video might be a little confusing at first. The initial bit, with the bright color palette, is from Diablo 3; at the 30 second mark, it flips to the more muted tones of Diablo 4. Also in keeping with Diablo 4, the passage of time has not treated the camp well: It has been utterly destroyed and abandoned.
The Reddit post doesn't contain any details about where the hidden camp is or how Fearlessmojo found it—fortunately for those who want to see it for themselves, they shared an image of the map location in a follow-up post. "I first noticed the waypoint that wasn't interactable so I was a bit confused, but then it clicked!" they wrote.
It does look to be a little out of the way, eh?
This isn't the only callback to a previous Diablo game—The Butcher, the terror-inducing first boss from the original Diablo is back too, and literally worse than ever because he can spawn in dungeons at any time. But much like the old-school music in Diablo 4's early stages, he's basically unavoidable: Sooner or later, everyone is going to see him. The discovery of the Hidden Camp, on the other hand, has players thinking more about other possible secrets in Diablo 4, and specifically whether a cow level might be stashed away somewhere.
For those unfamiliar with the old lore, the original Diablo was rumored to have a secret "cow level" that players could access by clicking on one of the cows in Tristram a certain number of times. There was no such level (it was really just a way to mess with people by convincing them click repeatedly on a cow for minutes at a time, because the internet didn't really exist back then and so we had to come up with more novel ways of tormenting our fellow gamers) but the story persisted, and became known well enough that Blizzard actually did put a secret cow level in Diablo 2, the Moo Moo Farm, packed with Hell Bovines led by the Cow King.
Diablo 4 GM Rod Fergusson has previously said that there is no Cow Level in Diablo 4, although he allowed for the possibility that one might be added in the future. But not everyone is convinced—in part because of this message in the game, posted by redditor The_Russman.
"The Oxen Gods stand as guardians to this sacred fountain. It is said that one who presents a worthy offering cleansed in these waters may gain their blessing."
Without context, it's harmless flavor text; with it, however, it's got dozens of redditors believing that the truth is out there, and working hard to crack the code.
There's another big callback to an earlier game floating around out there too, but it's much rarer and harder to find: Harlequin Crest, the greatest hat in all Diablo, has made the jump from past Diablo games to the new one. It's incredibly useful for every class, and also incredibly hard to find—the current assumption is that you have to be at least level 90 to even have a chance of it dropped.