Among all collectibles in DOOM The Dark Ages, Codex Entries can be some of the hardest to find. They are scattered across 18 of the 22 chapters of the game and reveal important plot elements, character stories, and information about the game universe.

If you're interested in delving deeper into the game's lore and want to achieve the accomplishment for collecting all items, then searching for each of these entries is inevitable. Below, we will guide you through all the locations with Codex Entries in the game. For better understanding, use the map images to determine DOOM The Dark Ages Codex locations.

Also, remember that all collectible items appear on the map if you are nearby.

Chapter 1 — Village of Khalim Codex Entries

Codex #1 — Doom Slayer

In the first chapter of DOOM: The Dark Ages — Village of Khalim — you can find two Codex Entries. One is located in an area by the seaside. To reach it, head right along the path to the rock situated in the middle of the water. Then climb the wall, follow the path, and climb again — this time on another wall. At the edge of the cliff, you will find the entry.

Codex #2 — Village of Khalim

Near the end of the chapter, after defeating the demons on the beach to weaken the red force field, look for a wall you can climb on the right. There, in a shrine, will be the Village of Khalim Codex Entry.

Chapter 2 — Hebeth

Codex #3 — Hebeth

After dealing with the first wave of imps, enter the room with green trim on the doors. Upon entering, you'll see a trail of health recovery resources. To the left, there are boxes — jump over them and proceed straight to reach a hidden area with the Hebeth Codex Entry.

Chapter 4 — Sentinel Barracks

Codex #4 — Sentinel Barracks

Before the second Sentinel Shrine, which you need to visit as part of the story, there's a path to the left with gold scattered along it. Do not enter the open room ahead; instead, follow this path. At the end, you will find the next Codex Entry.

Chapter 5 — The Holy City of Aratum

Codex #5 — The Holy City of Aratum

After finding the Super Shotgun, look for a passage that leads outside to wooden structures. There you'll see a red chain that you need to break with a shield, after which a bridge will lower. Then hit the green symbol with the shield to push a box and climb onto it. Simply move forward and descend into the room through the door arch. Kill the local cultists. Then descend the stairs opposite another red cross — there will be the Codex Entry.

Codex #6 — Deag Loric

The next Codex page in DOOM: The Dark Ages can be found in the lower section of the Hell Carrier. After breaking through the gates, defeat the enemies and descend. You'll see a trail of gold, at the end of which is another Codex page.

Chapter 6 — Siege – Part 1

Codex #7 — Siege Part 1

In the location where a Titan battles an Atlan in the background, climb up the metal beam next to the cliff — the Codex Entry will be on it.

Codex #8 — Kreed Maykr

On one of the cliffs where you find a collectible toy, look down and jump there. There will be a trail of gold, at the end of which is a Codex page.

Chapter 7 — Siege – Part 2

Codex #9 — Siege Part 2

You need to find the purple key and use it to unlock the gates to the inner courtyard (a secret area). Defeat the enemies inside to obtain the Siege – Part 2 Codex Entry.

Chapter 8 — Abyssal Forest

Codex #10 — Abyssal Forest

Upon reaching the area that requires a yellow keycard, continue until you see a large tree with a crack in its trunk. Break it with a shield to access the Codex Entry inside.

Chapter 9 — Ancestral Forge

Codex #11 — Ancestral Forge

At the start of the level, head northwest and look for a ledge you can descend to. There will be the Ancestral Forge Codex Entry.

Codex #12 — King Novic

Later, after activating the lift with the shield, look around — you'll see a red breakable object. Destroy it to create a platform. Jump onto it and reach the King Novik Codex Entry on one of the adjacent platforms. One of them will also have a weapon skin.

Chapter 10 — Forsaken Plains

Codex #13 — Prince Ahzrak

First, find the pink secret key and open the gates in the center of the map. Deal with the enemies inside and take the Prince Ahzrak Codex Entry.

Codex #14 — The Forsaken Plains

To find the second Codex Entry in this chapter, go right from the Sentinel Shrine and follow the golden trail through traps and fire jets.

Chapter 12 — Sentinel Command Station

Codex #15 — Sentinel Command Station

As soon as you exit the red ventilation tunnels, pay attention to the right wall. There will be a broken section, inside which is the Sentinel Command Station Codex Entry.

Chapter 14 — Spire of Nerathul

Codex #16 — Spire of Nerathul

In the mission to deactivate the second Stasis Emitter, look for a ledge near the drained pool — there will be the Spire of Nerathul Codex Entry.

Codex #17 — Serrat

Later, during the ascent of the tower to free the Old One, instead of turning left at the sign, go straight — to the Codex Entry.

Chapter 15 — City of Ry’uul

Codex #18 — City of Ry’uul

After using the first jump pad on the level, note the ledge on the left. Instead of following the marker, descend and follow the hidden path. Behind the door, you will find the City of Ry’uul Codex Entry.

Chapter 16 — Kar’Thul Marshes

Codex #19 — Witch

Near the central part of the map, find a group of rocky platforms. Jump onto the one with armor and look to the left — behind bars, you'll see a blue button. Activate it with a shield to open the door to the Witch Codex Entry.

Chapter 17 — Temple of Lomarith

Codex #20 — Temple of Lomarith

At the beginning of the level, after diving into the water section, find a nearby broken ship. Swim inside to find the next Codex Entry in DOOM: The Dark Ages.

Chapter 18 — Belly of the Beast

Codex #21 — Commander Thira

After completing the task “Destroy the Organ,” pay attention to the back of the room. In a recess in the wall is another Codex Entry.

Chapter 19 — Harbor of Souls

Codex #22 — Harbor of Souls

On the main path of the level, look to the left — you'll see a ledge next to the fires. That's where the first Codex Entry of this chapter lies. It's impossible to miss unless you're completely inattentive.

Codex #23 — Hell Priests

Before the final part of chapter 19, explore the area behind and find a room with hanging chairs and blue fires. Instead of heading to the game's finale, circle around the tunnel from the other side, where another Codex is located.

Chapter 20 — Resurrection

Codex #24 — Resurrection

After finding the yellow key in the tower, open the door right below it. The Resurrection Codex Entry will be next to the collectible toy Cosmic Baron.

Codex #25 — Commander Valen

Later, when you land on the Kreed ship, immediately turn around. At the edge of the platform, behind the dragon, you'll find another Codex Entry.

Chapter 22 — Reckoning

Codex #26 — Marok

At the start of the final mission, after breaking through the green gates with a shield, you'll enter a tunnel. Go right instead of engaging in battle. In a niche hides the last Codex Entry in the game.

What Happens if You Collect All Codex Entries DOOM The Dark Ages

Of course, DOOM: The Dark Ages doesn't force you to collect these entries, but they significantly enrich the gaming experience. Codex Entries reveal the lore of characters and locations, describe factions, and deepen the mythology of the DOOM universe. If you collect all the mentioned entries, you will earn the Lore Nerd achievement DOOM The Dark Ages, bringing you closer to 100% game completion.