Hi,
Yes "Class" is the concept that will help you achieve Object Oriented Design. In playmaker, a given FSM can be seen as a class.
I would recommend you study "prefab" if you have not yet used them in this game. Basically you will create a single cube "behavior" acting as a reference for the other. to create the board you will simply instantiate this prefab to form that grid, and likely store a reference of the gameObject or even better the main Fsm of that prefab in an array.
Have you gone that far?
Your cube prefab will have several global events so that you can set and get its properties. for example:
"DEFINE AS MINE" would be the event you call on a cube so that it turn itself as a mine ( called during the init of the board
"COMPUTE SURROUNDING" would be a call to a cube so that it checks its surrounding cubes to find out the number of close mines.
"REVEAL" would be the event you call when the user click on it, and fire a series of logical step to.
"FLAG" would be the event when the user thinks that cube is a mine
Now to get information from a cube, for example when you check surrounding mines, you simply access variables you will have defined such as "IS MINE" "IS FLAGGED" "CLOSED MINES" etc and further walk your board to reveal an empty area for example.
Hope this helps,
Jean