When you eventually arrive in the Doom Slayer’s exceptionally titled home base, the Fortress of Doom, you’ll notice that it’s actually rather massive and contains over a dozen interactable rooms, plenty of easter eggs, secrets and collectibles to discover. Most of the helpful items and upgrades in the Fortress of Doom can be gathered up very easily by just opening up sealed doors using Sentinel Batteries, however, there are a couple of sneaky collectibles waiting to be located across the base itself.
Both of these are Doom Eternal cheat codes, and if you want every one of those in the whole game then you can follow that link for a guide to each one. We’ve also got a couple of unlockable extras that aren’t considered collectibles.
If you’re going back through the game in search of every secret then we’ve already made a Hell on Earth collectibles walkthrough and an Exultia collectibles guide to help you out. There are only two properly hidden collectibles on the Fortress of Doom, but one is particularly devious if you don’t know where to look.
Cheat code 1
If you’re staring out into space at the front of the ship then turn around and head into the next room that has a central chamber and stained glass windows around both borders. Look up and you should spot a floating question mark in a vent. To get there, look at the stained glass windows for a red bullseye – shoot it. This will open up a red jump pad, which you simply need to walk onto. This will fire you up into some vents, look around for a drop down right next to the secret.
Cheat code 2
Again, staring into space from the front of the Fortress of Doom there are two external towers that you can access by going down a floor. Go to the tower on the right (the one with the intact bridge). You need to use a couple of Sentinel Batteries to open up the vault, then once inside look left for a hole in the wall. Drop out of the hole, turn around, then dash into the opening with the collectible inside for another cheat cartridge.
Old school PC
This doesn’t count towards your overall progression, but if you’re curious about the old school PC, how to access it, and what’s on it, then check out our dedicated guide to the Doom Eternal secret PC password. We don’t want to spoil it for anyone.