were having a problem about database to be used. we are required to have a database that will store the current state of the game as well as the scores is it suitable if we use offline storage or use C++ as backend? please help
You need to use the Offline Storage API. It is a subset of MySql and it works fine.
and also the following game tutorial does exactly what you are looking for. It stores the highscores offline which can easily be extended to save any data you want ( the state of the game ). http://doc.qt.nokia.com/4.8/declarative-tutorials-samegame-samegame4.html
bq.store the current state of the game as well as the scores
you can make use of "QSettings":http://doc.qt.nokia.com/stable/qsettings.html#details as well.