Engine capabilities Blueprint never had — quaternions, subsystems and flexible struct data in one plugin.
Blueprint Unchained combines three complete Blueprint toolsets in one package. Build rotation logic without round-tripping through Rotator, create engine-managed subsystems without C++, and store different struct types in one variable with the missing nodes needed to use them.
Blueprint Quaternion
85 pure nodes under Math > Quaternion cover construction, conversion, composition, interpolation, swing-and-twist decomposition, angular queries, random rotations and raw component math. Every angle pin uses degrees, rotation operations normalize their inputs, and the library is BlueprintThreadSafe. The editor also gains a practical quaternion details row with Euler, axis-angle and raw component views.
Blueprint Subsystems
Create Blueprint-defined Engine, Editor, Game Instance, World, Tickable World and Local Player subsystems. Implement their lifecycle as Blueprint events, control which worlds create them, declare initialization dependencies and access them through Unreal Engine's standard Get Subsystem nodes. Discovery and cook integration keep otherwise-unreferenced subsystem assets in a packaged build.
Blueprint Instanced Struct
Use Unreal Engine's own FInstancedStruct as one variable that can hold different struct types. Typed wildcard Get and Set nodes include a struct picker, while query, comparison, text round-trip and array nodes let Blueprint inspect and organize the values. Native and Blueprint-authored structs are supported.
Each toolset can be used independently or combined. For example, a Blueprint subsystem can own an event queue of Instanced Struct payloads while quaternion nodes handle rotation data inside those events. There are no actors to place and no replacement data types to adopt. Full C++ source is included.
Documentation: Blueprint Unchained documentation