SightLine

Give your guards something to notice.

SightLine is a focused 3D stealth detection toolkit for Unity. Build awareness over time, let cover break line of sight, react to gameplay noise, and keep track of what each observer last saw. Reusable Detection Profiles keep sensing rules separate from the behavior that responds to them.

Start with one observer and one target. Set the view angle, range and detection timing, then connect suspicious, detected, lost and calm events to your own alarms, patrols, combat or UI. Custom inspectors show the current evidence and awareness so you can see why a target is visible, hidden, out of range or blocked by cover.

Make cover and visibility matter

Use up to eight sample points to distinguish partial exposure from full cover. Tune target visibility, optional distance falloff and a short loss-of-sight grace period. Place manual Shadow Zones where you want darkness to reduce visibility, without sampling scene lighting or requiring a specific render pipeline. Overhead 3D question marks and exclamation marks make suspicious and detected states easy to read.

Hear a location. Remember a target.

Noise Emitters and Noise Listeners turn authored gameplay events into hearing stimuli, with range, strength and wall attenuation, and can optionally make an observer suspicious. Multiple-target sensing maintains separate awareness and last-known positions, with priority-based focus and per-target state events. Last-known positions can expire after a configurable time.

Learn through nine demos

Explore Basics, Profile Comparison, Alarm Response, Partial Cover, Hearing, Multiple Targets and Detection Volumes. Then play Museum Heist or Distraction Route to see patrols, cameras, hearing, cover and a camera alerting a guard working in connected encounters. The examples show how sensing can drive gameplay and include their C# source.

Get from import to your first detection

A guided Getting Started tutorial opens directly inside Unity. Scene-setup actions, five reusable presets, live inspectors and an offline PDF manual help you configure a first observer and adapt the system to your own game.

SightLine includes editable C# source. It requires no third-party SDK, service, account or subscription. The runtime uses Unity 3D physics; the supplied demos include Default (Built-in), URP and HDRP variants with Unity UI.

Scope: SightLine supplies sensing and example responses. It does not include general-purpose pathfinding, a behavior tree, automatic light/shadow detection, microphone analysis, audio playback, networking or 2D physics support. Demo controls work with the Input Manager, Both, or Input System (New) through an optional backend that activates when the Input System package is installed. The nine demos have separate scene/material variants for all three pipelines.