Call of the Machine is the brand new 27-level campaign specifically created by MachineGames for the 2023 remaster of Quake II. Being the latecomer, it makes free use of all the assets (be it monsters, weapons, inventory items, textures or music) that were developed for the previous Mission Packs (i.e. 'The Reckoning' and 'Ground Zero') and adds a whole bunch of tricks of its own. As such, it is recommended to play it only after you have enough experience with the MPs in question - preferably after seeing both of them to completion.
This guide has been created to serve as a clean-cut visual aid for for getting all of the secrets in the MachineGames campaign (63 in total). Discovering the secrets by one's self is a huge part of the fun so it is recommended that you only refer to the guide to find out what you are missing instead of following it step by step. Though not marked as secrets, there are also many more items to be found in explosive crates or hard to reach spots so a thorough search of any given level is almost always rewarding.
The guide is laid out so that the numbering of the secrets is in line with the mostly linear flow of the game: where multiple paths are available, it is presumed that the player goes towards the objective first. In addition, due to the unit-based nature of the title, some of the secrets are only accessible upon returning to the same level at a later stage. In those cases, a later visit to the level in question can be identified by the tag (Continued) besides its name.
Of the two shots provided for the secrets, the first one covers the area it is to be found in while the second one shows a particular detail, which, in most cases, is the trigger itself. Additional tips are deliberately kept short to let the shots speak for themselves.
As with all things Quake II, playing on at least Hard difficulty is recommended for full effect.

Instead of following the example set by the id campaign, Call of the Machine progresses more akin to the original Quake (or MachineGames' own Dimension of the Machine, for that matter).
Its six units of varying length are self-contained episodes: the player is dropped to each one equipped with only a blaster to retrieve what the other marines before him failed to do: a data disk containing Strogg intel. The central portal found on the station that leads to the creator of the realm can only be activated after collecting and uploading all the disks in question.
The left chamber of the station holds the pods to ops Corpse Run, Laser Eyes and Wastelands, while the right one has the pods for ops Ruined Earth, Firewall and Darkest Depths. You are free to take them on in any order you wish, yet both the level selection screen and the actual filenames suggest an intended path. The guide follows this order and also recommends it.
One thing of note are the secret levels. Apart from the second, every unit has its own. Of these, the one for the third may be considered slightly more traditional and comes later during the unit. On the other hand, the other four follow the same formula: you are dropped in a gauntlet (or a 'trial run', as it is called in-game) and return to the previous level with extra supplies as long as you come out on top. Placed earlier during the units, their entry points share the same look: a plate with commander texturing. The supplies in question are most welcome, so it is better to take on these challenges as soon as they are available.

This unit consists of 6 levels that contain a total of 9 secrets.
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A GRAVE FOR DEAD GODS
1/4 - Use the rock pillar as a stepping stone to jump on top of the nearby cart and crawl in.
2/4 - Get into the pipe and follow the path all the way around to reach the semi-hidden item.
3/4 - Toss a grenade through the half-open gate into the opening on the floor.
4/4 - Shoot the commander plate and utilize the crates in the vicinity to reach the opening.
The teleporter within leads to the first secret level.
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THE CASALI EFFECT (Secret level)
This level has no secrets.
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MEGACORPSE IV
1/1 - Push both of the buttons next to the data disc alcove to be granted a suit of armor.
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THE DEATH GATE
This level has no secrets.
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GIVE ME BACK MY MOON
1/4 - Look for a vent to crawl in to your right in the hall leading to the blue door. In there, a certain part on the second line of the writing on the wall is actually a hidden trigger. Shoot it to open up an additional compartment. -- Credit goes to Zhnigo for noticing this.
2/4 - After getting the blue key, look for another vent downstairs and crawl in.
3/4 - Past the blue door, shoot the striped panel to your left to access the nearby suit of armor.
4/4 - Shoot all the four buttons in the second level of the drop to be granted a power-up.
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STROGG JAMMERS
This level has no secrets.

This unit consists of 3 levels that contain a total of 10 secrets.
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OUTER COMPLEX
1/4 - Take the upper path while swimming through the pipe to get a weapon in advance.
2/4 - Drop down to the left of the walkway and crawl towards the semi-hidden suit of armor.
3/4 - Activate the bridge, drop down and crawl into the opening next to the dead marine.
4/4 - Following on from the previous secret, cross the bridge back and go the other way. Drop down into the water from the corner and climb the ladder.
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SECURITY ANNEX
1/4 - Right at the beginning, dive into the pond and shoot the cracked panel to find a power-up.
2/4 - Get the railgun on offer and dive towards the bandolier residing in an alcove below.
3/4 - Following on from the previous secret, take the path where the dead marine is laying on.
4/4 - In the adjacent area, shoot the button found by another dead marine in the corner.
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COMMS BUNKER
1/2 - Right at the beginning, drop down onto the lower walkway from the stairs to the left.
2/2 - Down past the yellow door, take the next elevator and drop down next to the dead marine.
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Easter Egg
After realigning the satellite dish in Outer Complex but before returning to Comms Bunker, make another trek to Security Annex. Take the shortcut lift to the overlook in the initial area and drop down to the ledge on the left. Follow it around the corner and take the opening by the crates.
Be sure to return to Comms Bunker via the entrance in Outer Complex to not miss out the action.

This unit consists of 5 levels that contain a total of 20 secrets.
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ECHOES OF THE PAST
1/7 - Shoot the planks, move into the pipe and get the semi-hidden item to the right.
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RUINED EARTH
1/7 - Step into the tunnel underneath the ruin and shoot the planks above to get a weapon.
2/7 - Following on from the previous secret, get out from the other end of the tunnel to find an item. Further exploration of this path provides more supplies in advance.
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ECHOES OF THE PAST (Continued)
2/7 - Crossing the rather long hall, turn around midway and get the item in the pipe to the left.
3/7 - Get on the wheel then make a running crouch-jump onto the slide to reach an item.
4/7 - Once the canal exit is open, go back up and jump onto the other wheel. Drop down onto the plank holding it in place then make a running jump onto the hatch to reach the other side.
5/7 - Jump over the crates to get the power-up that can be seen in the pipe across.
6/7 - Get on top of the crates at the back then jump onto the other one to reach a suit of armor.
7/7 - Still in the same area, swim into the pipe to get the item residing at the other end.
A rather short trek through Ruined Earth leads to Strogg Mining Intake.
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STROGG MINING INTAKE
1/5 - In the hall under drill #1, get onto the crates to the right and crawl into the opening.
2/5 - Take the ladder under the walkway that leads to drill #6 and shoot the panel across.
If following on from the previous secret, that should be on your right midway through the hall.
3/5 - After shutting down drill #3, hop on the crate by it and take the ladder on the other side.
4/5 - On the way out, jump onto the crates stacked to the left and make your way across.
5/5 - Once out of the ship, shoot the bricks next to the dead mutant to reach a side area.
The hatch across the other end of the pipe within leads to the second secret level.
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PUMPING STATION 3 (Secret level)
This level has no secrets. As a side note, the item you are tasked to collect here is a variation of the secret item Ancient Head from the id campaign. A 'super adrenaline' of sorts, it adds 5 points to your maximum health upon picking it up.
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RUINED EARTH (Continued)
3/7 - From the overlook, make your way to the dead marine by using the pillar as a stepping stone. Make a running jump onto the bricks across and then get into the pipe around the corner. Be wary of the gap in the pipe in question.
4/7 - Following on from the previous secret, take the stairs in the previously drill-blocked path.
5/7 - Following on from the previous secret, turn back and dive into the drill hole by the stairs.
6/7 - Following on from the previous secret, jump through the window and return to the tracks. Check the side area found midway and look for an opening behind the crates at the corner.
7/7 - Shoot the explosive crate behind the stack at the corner and drop down into the opening.
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Easter Egg
Before moving on to Way of the Marine by going through the red door, return to Echoes of the Past via the underground entrance (near secret #3 on this level). Make your way to the area above the canal exit (secret #4 on that level) and crawl into the opening found on the left side to meet an old friend once more... He just keeps living on and on.
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WAY OF THE MARINE
1/1 - Get on the sideways crate to the right and make your way to the other side of the stack.

This unit consists of 4 levels that contain a total of 11 secrets.
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UPLINK TOWER
1/3 - Shoot the button visible behind the crates to open up a hidden compartment nearby.
2/3 - Shoot the bar holding the crate to the right in place and utilize the crate to reach the door.
3/3 - Shoot the bar holding the crate to the left in place and use the nearby barrier as a stepping stone to make your way to the door above.
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HEAVY WATER
1/3 - Take the open path at the beginning and check the gate next to the one to installation.
2/3 - In the launch systems control room, get on top of the crates to the left and push the button. Get underneath the stairs through the newly-revealed opening and shoot the commander plate. The teleporter within leads to the third secret level.
Since the remaining part of this level is rather short and you are required to return here to open up the exit, it is recommended to leave the secret level aside until you are finished with this one.
3/3 - Going through the supply station, shoot the cracked console found on the side of the pillar.
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MCGEE STATION (Secret level)
1/2 - Shoot the striped panel found in the compartment next to the lasers at the end of the hall.
2/2 - Once teleported, reach the item laying out in the open. If it proves tricky, do a rocket jump.
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JUNKYARD
1/3 - Before taking the ladder up, drop down into the water and get the railgun in the pipe.
2/3 - Go up the slope, turn around and make a running jump into the pipe across.
3/3 - On the top floor of the complex, check the corner behind the crates to find a suit of armor.

This unit consists of 4 levels that contain a total of 8 secrets.
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SURFACE INFILTRATION
1/2 - Go up the tower, shoot the cracked grate next to the railgun and jump in.
2/2 - Turn around on the stairs to the control room and make a running jump into the opening.
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STROGG FLESH LABS
1/2 - After destroying the nodes, take the ladder up and get on top of the vent. Reach the commander plate in sight and shoot it. The teleporter within leads to the fourth secret level.
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BAKLAVA (Secret level)
1/2 - At the beginning, make your jump to the right and get the item below as you pass by.
2/2 - Power down the yellow firewall and make your way to the item laying out in the open.
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STROGG FLESH LABS (Continued)
2/2 - Once the red lasers are out of the way, drop down into the ventilation shaft. Progression here lies beyond the cracked grate next to the pipe in the middle. Before going further, turn off the valve and take the other path. Now that the slime is out of the way, drop down through the destroyed grate to get the weapon within. Return to the ventilation shaft via the way you come.
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THE MAINFRAME
1/2 - After disabling the mainframe, get into the room across the transmitter and shoot the jumper switches found on the board to open up a hidden compartment.
2/2 - Following on from the previous secret, drop down and take the path that leads back to the entrance. Approach the panel behind the red door to face a literal mini-boss.

This unit consists of 4 levels that contain a total of 3 secrets.
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TOO DEEP
1/1 - Drop down to the rock pillar after taking the elevator and shoot the cracked grate next to the crates to get an invulnerability power-up. Save it till the very end for an unmarked secret.
Instead of rushing towards the exit, activate the invulnerability power-up and drop down onto the nearby lava. Shoot the commander plate around the corner to reveal a room full of supplies.
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TOO GREEDY
1/2 - Ride the elevator to its topmost point and shoot the commander plate. The teleporter within leads to the fifth and the final secret level.
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TURBINE (Secret level)
This level has no secrets.
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TOO GREEDY (Continued)
2/2 - Drop down on top of the piston from upper walkway and jump onto the platform at the top. Note that the secret trigger is not the suit of armor itself, but some floating point around it.
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FATALISM
This level has no secrets.

This level contains two secrets.
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1/2 - Once out of tunnels, look up and shoot the planks in the middle to get an item.
2/2 - Move to the other side of the pit and shoot the planks at the corner to get a power-up.
'Vengeance has been wrought upon the enemy, and you are lost in the infinite cosmic void.'
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Guides for the original, MPs 1/2, N64/PSX and Zaero following the same format seen here are also available to accompany this one. Check them out if you are in for a completionist's run: