[Wowfunhappy]

What I'd do:

• All squares start off as unchecked boxes.

• Marked squares are partially-checked boxes.

• Revealed bombs (e.g. player lost, show the board) are fully checked.

• Uncovered squares are deleted, and a number is placed in the space as simple text.

You could absolutely argue the last point is cheating, but, meh, I feel it's within the spirit of the idea.

(Undecided on whether to use disabled checkboxes to mark the perimeter of the playing field; I'd have to try it and see what felt right.)