In Doom Eternal’s sixth mission, “Arc Complex,” there are 25 exploration items across the level.
While some items, like Modbots and codex entries, appear on the map automatically as you explore, a hidden or secret item won’t show up unless you happen to walk nearby. You’ll know you’ve passed by one of these collectibles when you see a white question mark on the map or a large, floating question mark in the game world.
In this guide, we’ll show you where to find all hidden items: three toys, a cheat code, a hidden Modbot, one hidden Sentinel Crystal, one hidden lore, two hidden albums, and one hidden Secret Encounter. Below, you’ll find maps, locations, and explanations of how to reach every question mark and find each secret in this level of Doom Eternal.
Arc Complex toy locations
There are three toys hidden across the Arc Complex.
Arc Complex // Toy 01: Mancubus
Right after dropping from the elevator at the beginning of the level, you’ll fight off several enemies. At the end of the hall, a Mancubus enemy will burst from an office. Hidden in the back of the office is Toy 1: Mancubus.
Arc Complex // Toy 2: Cueball
In the area where you get the Automap and there’s a Slayer’s Gate, you can double jump and dash across the gap to find a Sentinel Battery and Toy 2: Cueball.
Arc Complex // Toy 03: Whiplash
Before you fire any of the turrets, while you’re making your way up the apartment buildings, you’ll come across a small hallway hidden in the debris. Walk through the gap in the rubble to find Toy 3: Whiplash.
Arc Complex Cheat Code location
There is one cheat code in the Arc Complex.
Arc Complex // Cheat code: IDKFA
In the area immediately after you find the Automap and near the Slayer Gate, you’ll enter another building where an enemy pops out of the floor. Look into hole in the floor to find the Cheat Code: IDKFA.
Arc Complex hidden Modbot location
There is one hidden Modbot in the Arc Complex.
Arc Complex // Hidden Modbot
In the area right after where you get the cheat code above, you’ll run across a station that plays an important audio log. To the right of the station is a breakable wall. Punch through to find a room with the hidden Modbot.
Arc Complex hidden Sentinel Crystal location
There is one hidden Sentinel Crystal in the Arc Complex.
Arc Complex // Hidden Sentinel Crystal
Partway through the level, you have to jump a large gap to enter another building. Once you’ve entered the building, you could move forward, but to find the hidden Sentinel Crystal, jump over the pile of rubble pictured above to find a breakable wall.
Follow the stairs up to find a piece of hidden lore, and further up you’ll find the hidden Sentinel Crystal to the right of the boarded up door you can smash through.
Arc Complex hidden lore locations
There are two pieces of hidden lore in the Arc Complex. hidden lore 1 is detailed just above, where the hidden Sentinel Crystal is. The other is below.
Arc Complex // Hidden lore 2
At the end of the tunnels that are filled with electricity, you’ll come across a door you cannot access. At the opposite end of that tunnel, is a control room. Flip the switch there to open the previously closed door. Beyond the door is the secret piece of lore.
Arc Complex hidden album locations
There are two hidden albums in the Arc Complex.
Arc Complex // Album 1: Quake II: Quad Machine
Following the directions to get to the hidden lore above, you’ll notice a shaft you can drop down in that area.
Right next to the wall that says “Do not shoot” will be a question mark hidden behind some boxes. Pick it up to grab the hidden album: Quake II: Quad Machine. Also in this room is this level’s hidden Secret Encounter.
Arc Complex // Album 2: Quake III - Intro
After you’ve used the second cannon, you’ll make your way to a two-story parking garage to fight some enemies. On the top floor, tucked in a side area, is this mission’s second hidden album: Quake III - Intro.
Arc Complex hidden Secret Encounter location
There is one hidden Secret Encounter in the Arc Complex.
Arc Complex // Secret Encounter
The hidden Secret Encounter is in the same exact area as both hidden lore 02 and hidden album 02 are above.
Arc Complex Slayer Key location
A Slayer Key is hidden in the “Arc Complex.” You need the Slayer Key to open the Slayer Gate, which gets you one of the six Empyrean Keys.
Vargo Convention Center // Slayer Key
In the back area of this battle arena near the Automap station, you’ll notice a Slayer Gate. Adjacent to it, in an area above you, you may notice a purple glow. That’s where the Slayer Key is.
To get it, simply jump to the climbable wall opposite of the glowing room, turn around, and jump into the room to grab the Slayer Key.