Stealth Enhancer

The  is one of the augmentations in Deus Ex: Human Revolution.

Description
The Stealth Enhancer grants the user the ability to increase their perception, displaying stealth-related information; such as noise generated by the user, enemy cones of vision, last known location (where enemies saw the user) and lastly a mark and track ability (used to track targets from a distance, even if invisible).

Use: Displays stealth-related information; such as cones of vision, known location and allows to mark and track targets at a distance.

Info: Initially the Stealth Enhancer augmentation only includes an ambient noise feedback indicator, projected directly onto the user's optical display.

Activation Cost: 2

Noise Feedback

 * Upgrade Requirement: Stealth Enhancer Augmentation
 * Upgrade Cost: N/A
 * Use: Displays the range at which the noise you produce travels
 * Activation: Automatic
 * Energy Consumption: None
 * Info: The enhanced 'Noise Feedback' functionality of the Stealth Monitor gives its user a real-time representation of personally-generated noise levels and their detection range. This information appears as a pulsating circle radiating from your position on the radar.

Cones of Vision

 * Upgrade Requirement: Stealth Enhancer Augmentation
 * Upgrade Cost: 1 Praxis Point
 * Use: Displays the enemy's cones of vision
 * Activation: Automatic
 * Energy Consumption: None
 * Info: The enhanced 'Vision Feedback' functionality of the Stealth Monitor allows experienced users to define and track the sight cones of enemy targets (either organic or inorganic). These vision cones appear on the radar display.

Last Known Location Marker

 * Upgrade Requirement: Noise Feedback Upgrade
 * Upgrade Cost: 1 Praxis Point
 * Use: Once detected, displays an icon at the location the enemy last saw you
 * Activation: Automatic
 * Energy Consumption: None
 * Info: This stealth upgrade gets activated upon detection by enemy forces and monitors the opponents' behavior and eye movements in order to determine whether they've lost sight of the user or not. Once an evasion is successful, the on-board software places a marker at the approximate location where enemies are expecting the user to be. This marker appears only in the user's field of view, via augmented reality, and helps them slip away unnoticed by showing him where the enemy thinks he is.

Mark and Track 1.0

 * Upgrade Requirement: Noise Feedback Upgrade
 * Upgrade Cost: 1 Praxis Point
 * Use: Displays an icon over up to three targets, so they can be easily tracked.
 * Activation: From a distance, place the reticule over an opponent and hold the Interaction Button to mark him.
 * Deactivation: Aim at the tracking icon and hold the Interaction Button.
 * Energy Consumption: None
 * Info: By tagging targets, the user is able to track their movement up to a range of a 100m. An icon appears in the users field of view, displaying the target's location at all times, making stealth operations that much easier. This basic version can track up to 3 targets simultaneously.

Mark and Track 2.0

 * Upgrade Requirement: Mark and Track 1.0
 * Upgrade Cost: 1 Praxis Point
 * Use: Displays an icon over up to five targets, so they can be easily tracked.
 * Activation: From a distance, place the reticule over an opponent and hold the Interaction Button to mark him.
 * Deactivation: Aim at the tracking icon and hold the Interaction Button.
 * Energy Consumption: None
 * Info: More experienced users will be able to track up to 5 targets. Marked targets can also be unmarked, in order to free up marking slots.

Mark and Track 3.0

 * Upgrade Requirement: Mark and Track 2.0
 * Upgrade Cost: 1 Praxis Point
 * Use: Displays an icon over up to seven targets, so they can be easily tracked.
 * Activation: From a distance, place the reticule over an opponent and hold the Interaction Button to mark him.
 * Deactivation: Aim at the tracking icon and hold the Interaction Button.
 * Energy Consumption: None
 * Info: The mark and track software is ultimately able to follow up to 7 targets at once. However, only users who have invested the time and effort getting familiar with this feature will be able to unlock its full potential.

Gameplay
One of the augmentations that the player has to manually unlock at the cost of 2 praxis points. At first it can seem a pretty low-priority augmentation as opposed to the Icarus Landing System or other augmentations. Especially at the first level, which only tracks how much sound you are making, which is useless since most stealth players will move either crouched or from cover to cover. Similarly, the Last Known Position system will also not be used by stealth players. It does, however, include a counter, indicating the time until the alarmed status of enemies expire, which may help non-stealth players. The usefulness of this augmentation shows later down the tree, with the cones of vision (indicating enemy vision cones on the radar) and especially the Mark & Track system, allowing the player to track targets (even if while they're invisible).

In the long run however, it all depends on the play style. Cones of vision can be useful, but enemy vision can be judged using only the radar system. As for invisible units, they aren't of any concern when playing stealthy, since they aren't cloaked unless attacking you and even then (specifically boss battles) they can be seen due to light refraction around their bodies.