I have two ideas about possible Final minor improvements,
which would make the game just the Perfect
:
1) Choose the side : it's quite strange that you can't play for black side, only for white.
(White side requires offensive strategy, but Black - defensive)
It could be asked at the main menu, after the level of difficulty is selected.
2) Move sound : for example, you've chosen the Hard level,
and want not only to play in Chess, but also to read a book or newspaper.
(smart opponent will be thinking carefully, up to several minutes)
With the Move sound, it will not be necessary to check every minute
if it's your turn now or player is still thinking.
I have a good move sound
(check the attachment)