Uploaded August 2025 | Updated September 2026, 57 minutes ago

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Hierarchical State Machines (HSMs) offer a powerful way to structure complex game logic by organizing states into nested layers of behavior. In this video, we build a fully functional HSM system in Unity from the ground up, starting with core concepts like state activation and transitions, then layering in a robust transition sequencer that acts as a mini-orchestrator for running activities during entry and exit. Along the way, we implement features like asynchronous delays, sequential and parallel phases, and show how to keep your state logic composable and testable. This is an advanced, code-intensive walkthrough designed for developers who want precision control over game state and transition flow.

Inspired by:
Matt King - github.com/matt-tekly/tekly-packages/tree/main/Packages/ca.tekly.treestate
Crash Konijn - crashkonijn.com

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▬ Contents of this video ▬▬▬▬▬▬▬▬▬▬

0:00 Hierarchical State Machine Overview
1:30 State, Statemachine and Sequencer
8:00 PlayerStateDriver
11:07 StateMachineBuilder
12:55 Concrete States
18:12 Basic Sequencer
23:47 Activities
26:24 Sequential vs Parallel

*Source code:* github.com/adammyhre/Unity-Hierarchical-StateMachine

More Useful Code:
github.com/adammyhre?tab=repositories
Unity Utility Library: github.com/adammyhre/Unity-Utils
Lock Inspector Hotkey: gist.github.com/adammyhre/4754f731a93bf1cab0d1385ccfa23642

*Other Recommended Tools* _(Affiliate Links)_
Scene Notes - assetstore.unity.com/publishers/87819?aid=1101lw3sv
DarkMode for Unity Editor - assetstore.unity.com/packages/tools/gui/darkmode-for-unity-editor-on-windows-281842?aid=1101lw3sv
Beautify - assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/beautify-3-advanced-post-processing-233073?aid=1101lw3sv
Umbra Soft Shadows - assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/umbra-soft-shadows-better-directional-contact-shadows-for-urp-282485?aid=1101lw3sv
Wingman - assetstore.unity.com/packages/tools/utilities/wingman-your-inspector-s-best-friend-303181?aid=1101lw3sv
Favorites Window - assetstore.unity.com/packages/tools/utilities/favorites-window-123487?aid=1101lw3sv
Logwin - assetstore.unity.com/packages/tools/utilities/logwin-log-debug-values-tracker-149558?aid=1101lw3sv
TimeScale Toolbar - assetstore.unity.com/packages/tools/utilities/timescale-toolbar-291564?aid=1101lw3sv
Odin - assetstore.unity.com/packages/tools/utilities/odin-inspector-and-serializer-89041?aid=1101lw3sv?aid=1101lw3sv
Odin Validator - assetstore.unity.com/packages/tools/utilities/odin-validator-227861?aid=1101lw3sv
Hot Reload: assetstore.unity.com/packages/tools/utilities/hot-reload-edit-code-without-compiling-254358?aid=1101lw3sv
Better Hierarchy: assetstore.unity.com/packages/tools/utilities/better-hierarchy-272963?aid=1101lw3sv
Better Transform: assetstore.unity.com/packages/tools/utilities/better-transform-size-notes-global-local-workspace-child-parent--276554?aid=1101lw3sv
Better Mesh Filter: assetstore.unity.com/packages/tools/utilities/better-mesh-filter-266489?aid=1101lw3sv
DevTasks - Offline Project Manager - assetstore.unity.com/packages/tools/utilities/devtasks-offline-project-manager-307257?aid=1101lw3sv
Editor Console Pro: assetstore.unity.com/packages/tools/utilities/editor-console-pro-11889?aid=1101lw3sv
Any Object Finder: assetstore.unity.com/packages/tools/utilities/any-object-finder-286455?aid=1101lw3sv
Clipper PRO: assetstore.unity.com/packages/tools/utilities/clipper-pro-the-ultimate-clipboard-277112?aid=1101lw3sv
Kybernetic Tools: assetstore.unity.com/publishers/16747?aid=1101lw3sv
Sisus Tools: assetstore.unity.com/publishers/41398?aid=1101lw3sv
Prime Tween - assetstore.unity.com/packages/tools/animation/primetween-high-performance-animations-and-sequences-2529607?aid=1101lw3s
Rabbit Logger - assetstore.unity.com/packages/tools/utilities/rabbit-logger-305396?aid=1101lw3s

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