The first mission of DOOM: The Dark Ages throws you right into the carnage, but it also hides a surprising number of secrets for an introductory level. Getting 100% completion requires finding all six secret areas, which contain two Demon Toys, two Codex Pages, a Weapon Skin, and multiple Life Sigils. This guide provides a direct, step-by-step walkthrough to ensure you leave the Argent Breach with every last item accounted for.
Your First Secret: The Hidden Life Sigil
After the initial combat tutorials where you master the shield block, parry, and charge, you’ll fight through several waves of fodder demons. Following these encounters, you'll proceed until you acquire the Power Gauntlet, your devastating new melee ability. The game will funnel you through a combat arena to test it out. Once the demons are cleared, your objective marker will point you up a clamberable wall and into a room on the left.
Ignore it. Before proceeding, look to the left of that main path. You'll spot a section of wall made of splintered wood. This is a breakable environmental piece. A simple melee strike or shield charge will shatter it, revealing the game's very first secret area. Head inside to claim a Life Sigil, an invaluable item that grants you an instant revive upon death. It's an easy secret to miss if you're just following the objective marker, but crucial for building up your safety net.
DOOM: The Dark Ages in-game screenshot
The Blue Key and a Locked-Away Toy
Progressing from the first secret, you'll soon find yourself in a larger combat arena with a gate sealed by a blue lock. Your new objective is to find the Blue Key. Follow the markers through corridors, taking out the demons that spawn to block your path. You'll eventually smash through a breakable wall and drop down into a lower passage.
This path leads you through a tutorial on parrying environmental 'Hell Surges'—green energy waves you must block with precise timing. After successfully parrying the waves, you'll face a mini-boss designed to teach you about Glory Strikes, non-lethal stuns that can alter an enemy's function, like dismounting a rider from their beast. Defeat it, and the Blue Key is yours for the taking.
Here's the critical step: once you have the Blue Key, backtrack towards the locked blue gate but do not go through it yet. On your way back, you'll notice a previously locked door that is now accessible with the key you just picked up. The Automap will likely reveal a question mark here. Open this door to find the mission's first collectible: a Demon Toy. With the toy secured, you can now return to the main gate and use the Blue Key to proceed to the mission's central hub.
Clearing the Four Demonic Portals
The next section opens up into a large, multi-tiered arena with a central sealed door and a new objective: destroy four Demonic Portals. You can tackle these in any order, but for a systematic clear, we’ll proceed clockwise, starting from the portal to your immediate left. Each portal is guarded by a host of demons, and clearing them all will seal the portal.
After clearing the second portal on your clockwise path, you'll be funneled through a narrow hallway where you'll be ambushed. A well-placed shield charge can clear out the densely packed enemies. Beyond this ambush, you'll enter another arena where a drop pod delivers your second weapon: the Shredder, a fully automatic machine gun. The game encourages its immediate use by spawning waves of enemies perfect for shredding. After this fight, you'll be positioned to find several more secrets before tackling the remaining portals.
DOOM: The Dark Ages in-game screenshot
Secrets of the Central Arena
With the Shredder in hand and two portals down, it's time to scour the area for its hidden collectibles before finishing the main objective. Use the third portal's location (the next one in your clockwise path) as a reference point.
Secret 2: Weapon Skin
Facing the third portal, look towards the center of the main arena. You'll see two cliffs that nearly meet. Instead of jumping across the gap, you need to perform a running sprint-jump into a hole in the side of the cliff face. You won't make the jump without sprinting. Once inside, a swarm of enemies will spawn. Use the explosive barrels to dispatch them quickly, then claim your reward at the back of the cave: a new Weapon Skin.
Secret 3: Soldier Toy
Return to the third portal's location. Go to the left of the portal, right up to the cliff's edge, and carefully drop down. You'll land on a hidden ledge that isn't visible from above or on the Automap. Follow this secret path to find the second and final collectible toy for this mission, the classic Soldier Toy. An enemy will spawn as you try to leave, so be prepared.
Secret 4: The Secret Key and a Life Sigil
After clearing the third portal, climb up the nearby cliff edge. Here you'll find the Secret Key, glowing conspicuously. This key opens the large, sealed door right in the middle of the entire arena, the one you likely noticed when you first arrived. Backtrack to this central door, use the key, and step inside to claim another Life Sigil. This also counts as a secret area found.
The Final Push and Last Collectibles
With all the central arena's secrets claimed, it's time to finish the job. Use the nearby launch pad to propel yourself towards the fourth and final Demonic Portal. Obliterate the demonic resistance to close it. This will open the main exit door for the mission, but do not go through it yet. We still have two secrets left to find.
Secret 5: First Codex Page
From the spot where you destroyed the fourth portal, turn around and go straight through where the portal once stood. Tucked away to the right is a secret path with a clamberable wall. Scale it to reach a high ledge overlooking the arena. Here you’ll find the mission's first Codex Page, offering a bit of lore on the Doom Slayer.
DOOM: The Dark Ages in-game screenshot
Secret 6: Final Codex Page
Now you can finally proceed towards the mission exit. You'll fight through one last combat arena before reaching the end-of-level icon. After clearing the enemies, but before you interact with the final objective, scan the walls of the exit path. On your right-hand side, a bit hidden from view, is one last clamberable wall. Ascend it to find a small final alcove containing the last secret: the second Codex Page. With this, you have officially found everything.
Your Work is Done
With all six secrets, two toys, two codex pages, and the weapon skin collected, you are now clear to finish the mission. Proceed to the final objective, man the massive cannon, and bring down the Titan looming in the distance. Completing this sequence will trigger the final cutscene and the mission summary screen, which should proudly display 100% completion. You're now ready to carry the momentum into Mission 2, fully upgraded and with a clean record.