A key is an item commonly found in Submachine games that help unlock doors to rooms and other parts of the Subnet. There are a variety of different types of keys, each serving their own purpose.
Submachine 2: The Lighthouse features four different keys: the room key, sewer key, second floor key, and the digout key.
Room key[]
The room key is a key that is found in the sewers. It enables the player to unlock a room that shows a bathroom with the sewer key hanging on a rack.
Sewer key[]
The sewer key is used to gain entrance into the locked portion of the sewers. This key is found inside the room that is unlocked by the room key.
Second floor key[]
The second floor key is located inside the sewers. This key is used to gain access to the second floor of the lighthouse.
Digout key[]
The digout key is located in the portal room in the pile of rubble to the right. This key is used on a padlocked door on the first floor of the lighthouse.
Five different keys are featured in Submachine 4: The Lab: the door key, regular key, stone key, stone blocade, and the chest key.
Door key[]
The door key is used to unlock the door on the far left side of the attic. It is found in a pile of ash after using the chimney brush on the chimney outside.
Regular key[]
The regular key is used to unlock a door in the research base which houses a teleporter. This key is found hanging on a rack in the attic.
Stone key[]
The stone key is one of the two keys found in the ancient section that are used to allow a ladder to descend from a higher-up section. It is found on the ground level on the left after pulling the levers matching the description of the panel.
Stone Blocade[]
The blocade key is one of two keys found in the ancient section that are used to allow a ladder to descend from a higher-up section. It is found on the main level to the right.
Chest key[]
The chest key is a key that is used to open a chest in the ship. This key is inside of an orb that is collected in the looping traps. To get the key, the player must break the orb using the laser in the basement section.
There are two keys in Submachine 5: The Root: the rusty key and the lead casting.
Rusty key[]
The rusty key is used to open a panel containing one cipher plate. This key is found in 552+ (0,0) hidden behind a plate. The plate is taken off by a wrench.
Lead casting[]
The lead casting is found on the ground in the tunnel of the root area. It is used for accessing a wisdom gem. It is very similar to the three jewels from Submachine 0 and is most likely a copy of them.
Three keys are found in Submachine 7: The Core, but since they are all called keys, they can only be told apart by color. They are: silver, rusty, and teal. They are used to unlock: the box in the sanctuary that contains the wisdom gem, the room to the right in the upper floor of the Winter Palace, and the box in the Winter Palace that contains a solenoid.
Rusty key[]
The rusty key appears at the beginning of Submachine 8: The Plan in order to unlock the starting platform. The player finds the key hanging from the dock and uses it to unlock a trapdoor.
Stone Key[]
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This key, when assembled, serves the same purpose as the circular brass keys. It is found and used in the blue area of the pyramid. It was the first instance in the Submachine series of combining items in the inventory.
Circular Brass Key[]
This key opens a door acting like a wall. There are two of these found in Sub9. The first is used in the main part of the pyramid, and the second is used in a secret area in the pyramid only accessible in layer 8.
Brass Key[]
This key opens a barred door leading to Elizabeth's tomb. It is found in the room accessible from the karma portal in Murtaugh's tomb.
Chest Key[]

These three jewels are used on platforms of a statue of the Egyptian deity Anubis. Each of the three is found in its own respective room, though all are found in the same area.
Submachine: Future Loop Foundation contains one key.
Key[]

Submachine: FLF contains the Future Loop Foundation key plus an additional one, both labeled "key".
Key[]

Three keys are found in the Submachine Universe.
Crimson key[]
The crimson key is the key which is used for opening the mysterious door at the left end of the corridor. It is found in the corridor.
Laboratory key[]
The laboratory key is used to open the locked door in the lab (001). It is found in the radio lab.
Pyramid key[]

Trivia[]
- Submachine 10: The Exit does not contain any keys in its inventory, which is ironic considering that game contains the most items out of any in the Submachine series.