FS Stealth System 2

About FS Stealth System 2 – Unity Editor Tool & Plugin

Unity Stealth System and AI

FS Stealth System 2 adds perception-driven guard AI and systemic stealth mechanics to Unity projects. Guards can detect players through vision, hearing, and touch, build awareness gradually, investigate suspicious events, coordinate searches, and react to factors such as lighting, restricted areas, weapons, distractions, and visual evidence. The system also covers hiding, cover, body carrying and stashing, while its data-driven AI state machine provides a visual way to create new behaviors without writing code.

Perception and Detection

Guards use separate Vision, Hearing & Touch Sensors rather than relying on simple trigger zones. Primary and Peripheral Vision can have independent shapes, ranges, and detection speeds, while Hearing supports configurable sound priorities so gunshots can take precedence over footsteps or thrown objects. Optional NavMesh-based sound propagation can also allow walls to muffle noise, and Touch Detection immediately exposes the player when they bump into a guard.

Detection is not limited to whether a guard can see the player. Light-Based Concealment can calculate visibility from the actual scene lights, while Hiding Areas support concealment in tall grass, boxes, bins, containers, and other configured spots. Gradual Detection builds awareness over time and allows it to fade while the player remains hidden, with on-screen detection meters showing the progression.

Stealth and Guard Reactions

The Cover System automatically detects low and high cover around walls and crates, allowing the player to use cover to break a guard's line of sight. Guards can also respond differently according to Suspicion Factors, Restricted Areas, Hostile Areas, and Weapon Suspicion. Restricted Areas use escalating warnings before force is used, whereas entering Hostile Areas triggers immediate combat.

The Distraction System lets players throw objects or create sounds to draw guards away from patrols. Visual Evidence gives guards a reason to investigate dead bodies and other suspicious objects, while Body Carrying and Body Stashing let players remove bodies and place them in configured bins, dumpsters, crates, or containers.

Coordinated Guard AI

Guard behavior progresses through Suspicious Investigation, Alerted Investigation, and Trespassing Response. When one guard detects something, nearby guards can be alerted; some investigate while others spread through the area to search hiding spots. Procedural Search Behavior generates search points around the last known position, supporting area sweeps rather than sending every guard toward a single waypoint.

Contextual Dialogue gives guards situation-specific voice lines for events such as footsteps, gunshots, trespassing, and other events. Authored behavior can also be used to control specific AI behaviors and actions for different zones or moments.

AI Architecture and Integrations

The Data-Driven AI architecture uses a visual AI state machine with blackboard-based communication. This allows new behaviors to be created through the visual system without writing code. Built-in integrations work with the Shooter, Melee Combat and Parkour & Climbing systems, supporting gameplay combinations such as stealth takedowns, air assassinations, and ledge finishers.

The Stealth System is built on the asset's character controller and AI framework. Guards use its AI state machine, so adding the sensors to custom AI characters requires wiring those sensors into the existing behavior logic. Player-side features including crouch-based hiding, footstep noise, throwing distractions, body carrying, and cover rely on its controller; projects using a custom player controller need to handle that integration themselves.

Compatibility and Examples

The system is compatible with Unity 6000.0.77f1 using the Built-in Render Pipeline, Universal Render Pipeline (URP), and High Definition Render Pipeline (HDRP). Multiple demo scenes cover core stealth, trespassing, body carrying and stashing, and light-based stealth gameplay. Built-in Agent Skills provide step-by-step instructions for AI coding agents covering setup, character creation, and the major workflows.

Use Cases

• Stealth games where guards need vision, hearing, touch, gradual suspicion, distractions, and coordinated searches.
• Action games that add stealth sections alongside Shooter, Melee Combat, or Parkour & Climbing systems.
• Levels centered on environmental concealment, using lighting, tall grass, containers, cover, and body stashing.
• Projects requiring authored guard encounters alongside procedural searches and data-driven AI behaviors.

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