So I began by adding a new game screen, this screen will also allow access to the previously played (saved) games.
The undo and redo functionality also needed fixing, I think some of the refactoring I did with the model code broke it. I also added a clear button to the number picker that appears over the board when you click a square.
The final important thing to mention is the preloaded puzzles. The game now includes some puzzles such that the user does not have to generate some straight away, this is also useful at the moment with the generator not fully working.
I next hope to add support for saving the state of current games to disk as JSON, and a help section to identify and explain logic techniques to the user.