Turrets are mainframe devices which occur in K&O facilities at mission difficulty 2 and greater.

Turrets have vision in a 90 degree cone, and no peripheral vision. It will overwatch when an agent, a rescued prisoner, or courier enters its vision cone. Once a turret is overwatching, any action that would cause a guard to shoot while in its vision, including by other agents than the originally spotted agent, will cause the turret to shoot, dealing lethal damage to its target. Unlike guards, the turret will not track its target, allowing escape by simply moving out of its vision cone, but when it shoots it will turn to most directly face its victim.

Turrets provide soft cover, but do not give you soft cover against their own vision.

Turrets will always be adjacent to a power supply tied directly to it. Both a turret and its associated power supply can be hacked using Incognita. If the power supply is hacked, the attached turret can be turned on and off in Incognita view. A power supply next to a turret will always just affect the turret; it will never be wired to anything else. If the turret itself is hacked, it will provide its vision to the agency and shoot guards when turned on.

Turrets can be shot by both agents and guards with lethal weapons, permanently disabling them.

When a turret shoots, it creates a noise in a range of 8 tiles, causing nearby guards to investigate. This can trigger sound bugs in range (though this situation can only happen in Vault missions). A turret can shoot only once per turn, and has 2 bullets - it will continue to overwatch after it has used up its bullets, but it cannot shoot. A turret's bullets have armor piercing 2.

When a turret overwatches a guard, that guard will stop moving for that turn - this will usually result in the guard not being shot this turn, with a few exceptions. However, the guard is likely to be shot next turn when he tries to move unless the turret is turned off, or something else gets shot first. Once a turret has shot a guard, it will be identified as a traitor for as long as it is turned on and remains in agency control. If a traitorous turret is seen by a guard, they will overwatch it and become alerted; if they do so, they will always shoot it before it shoots them. The turret can be turned off to prevent it from being shot in this case.

If a turret is watching a place that you need to pass through, you'll need to either hack it, hack its power supply, use a cloak, or destroy the turret. Hacking the power supply is usually your safest bet as it neutralizes the turret and avoids drawing the attention of guards, though it's possible that a dangerous daemon on the power supply might change this calculation.

If you hack the turret itself, you risk it shooting a guard, causing an alarm level hit from the dead guard's heart monitor. In addition, it's likely that other guards will come to investigate the loud noise it makes. This will happen during the corporation's turn, so you may not be able to react to this. Once they arrive, both the turret and the body will alert guards if they see them. It is possible to kill key guards, such as Spec Ops, using turrets, which can be helpful if you're able to manage the risks. Draco can get mostly-free skill upgrades using turrets as well.

If you are able to hack both the power supply and the turret itself, you can use it to manipulate a single guard's movement by toggling it. Since guards stop when overwatched, you can use it to prevent a guard from moving somewhere you'd rather he not be, and then turn the turret off once you've safely moved away. You can even toggle the power on the turret every turn to cause the turret to overwatch the guard every turn without shooting him, making him move just 1 tile per turn. Beware though - if another guard enters the turret's vision while this is happening, that guard will be shot, likely resulting in the turret being overwatched.