ImportantKeys
'K' is maybe the most important - it displays two help screens with all functions
'H' displays a help ticker - maybe interesting when you are already more familar with the program
'I' displays a short Sudoku instruction page
'N' offers a new Sudoku game for you to solve
'A' alters the difficult level for the next Sudoku puzzle
'1-9' set a cipher in the field you want (see also Input modes)
'0' or Space deletes an entered number
Ctrl-'R' restarts the actual Sudoku Puzzle
'U' or Backspace undos the last change