Ue State Trees

State Trees are Unreal's data-driven alternative to Behavior Trees, built for both single-actor AI and Mass Entity crowds at scale. The architecture is clever: tasks and conditions are lightweight structs instead of UObjects, and execution context gets reconstructed each tick from persistent instance data, making parallel evaluation safe. You get hierarchical states with evaluators that run globally before transitions, plus a schema system that validates what data your tree can touch at edit time. The instance data pattern takes getting used to (all your mutable state lives in a separate struct), but it pays off when you're running thousands of entities. If you're migrating from Behavior Trees or building AI that needs to scale beyond a few dozen actors, this is the modern path forward.

skills.sh installs: 1.2K
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last updated: Aug 21, 2026

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Install

$ npx -y skills add quodsoler/unreal-engine-skills --skill ue-state-trees --agent claude-code

Installs into .claude/skills of the current project.

Files

UE State Trees

Target engine: UE 5.8. APIs below are verified against the 5.8 headers; older forms are listed under "Deprecated — do not use".

State Tree is a data-driven hierarchical state machine authored as a UStateTree data asset and executed from C++ through an execution context. Runtime types live in the StateTreeModule (plugin StateTree); actor-facing components and schemas live in GameplayStateTreeModule (plugin GameplayStateTree). Mass-entity behaviours add MassAIBehavior (plugin MassAI, Experimental in 5.8) plus MassEntity, MassCore and MassSignals. Add the modules you use to PublicDependencyModuleNames in your .Build.cs.