Here is a general overview of some of the more important directories in the project.
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├── data
│ └── workspace.json // an export of a basic Speech Sandbox Assistant setup
├── Creation Sandbox // the Unity project
│ ├── Assets // contains all project assets
│ │ ├── _Scenes // all game scenes
│ │ │ ├── MainGame
│ │ │ │ ├── MainMenu // the main menu scene
│ │ │ │ ├── Tutorial // the tutorial scene
│ │ │ │ └── Sandbox // the main sandbox scene
│ │ ├── Prefabs // the games prefabs
│ │ │ ├── CreatableObjects // all objects that can be created
│ │ │ ├── Tutorial // objects pertaining to the tutorial
│ │ │ └── Widgets // contains custom widgets (like VoiceSpawner)
│ │ ├── Scripts // all custom game scripts
│ │ │ ├── Controls // scripts related to the game controls
│ │ │ ├── Objects // scripts related to the objects that can be created
│ │ │ ├── SceneManagement // scripts related to manageing scene state
│ │ │ ├── Tutorial // scripts related to running the tutorial
│ │ │ └── UI // scripts related to any menuing
│ │ ├── SteamVR // the SteamVR plugin
│ │ └── VRTK // the VRTK plugin
│ └── ProjectSettings // contains configuration files for the project
For additional help understanding the code you can check out this blog written by Kyle Craig about how to implement this type of speech control in your own projects.