My favorite part of Wolfenstein: Youngblood is how much it feels like an Arkane game. Sure, Machine Games is billed as the primary studio, but I can feel Dishonored in Youngblood's explorable buildings and the totally unnecessary (but delightful) edible food realistically placed on plates in the homes I wander through. But tucked away in Youngblood is an overt reference to their stealth series that, as far as I'm concerned, is definitive proof that Bethesda games share a universe.
Youngblood's clever Dishonored easter egg is locked behind a door in Victory Boulevard that requires the Dieselwerk tool to open. You find a lot of these doors early on in Youngblood, and the only way to open them is continuing the story. During the Brother 2 mission, you find the Dieselwerk, a remote detonated grenade launcher.
Once you have it, head on back to the north side of Victory Boulevard and follow the path shown in the gif above. The door isn't far from the metro station, but there's an annoyingly long wave of enemies between you and it. If you're not high-leveled, it's worth sweeping the area of Nazis before continuing.
Once you find the door, blow it open with a grenade and then... yep, that's an Outsider rune!
It looks like the Outsider still has his followers, even in Nazi-controlled '80s Paris. That door could probably keep Corvo out, but not Jess and Sophia Blazkowicz. Other than a unique notification, you don't get anything special for picking up the rune. It would've been pretty amazing if you could cast Blink for the rest of the game.
But hey, the reference is cool enough on its own. Stepping through the door feels like a portal into Dishonored's sharp, watercolored world. Arkane may be moving on from Dishonored (I'm not bitter), but it's nice to see the reverence it has for its strange world. I also see it as a wink and nod to just how Arkane they got with Youngblood's level design.
If you're trying to check off everything from Youngblood's exhaustive list of collectibles, we have a handy guide to find all 41 Wolfenstein: Youngblood cassette tapes.