In folder Prefabs/UIs/Essential, all of them are the essential game objects to drag into an empty scene for chess game to run on Play Mode in an instant.
-The most basic group of script components needed to kick start a chess game. Sound effect is nested within its hierachy.
-Containing Common UI that can be reused by almost all scene such as promotion selection UI, current turn UI and game finishing UI panel.
-Containing all the basic UI to control chess game, including undo, redo, start game, quit game, etc. Basically all of the UI nested in this prefab hierachy is listened(see this section) by ChessGameBaseGUI script component. Only partial UI is listened by ChessBaseGUI which is attached as the base for ChessGameObjectBase prefab, simply replace the ChessBaseGUI with ChessGameBaseGUI script component for all of the button to work automatically.
Note : This prefab contain EventSystem in its hierachy, any EventSystem in Canvas gameobject created on scene should be removed since a scene cannot have two EventSystem component.