Hey, guys, I'm back into calcs!
I made a new game demo, this time of Sudoku!
Use the arrow keys to move the selection cursor. Press a number key (1-9) to enter a number in a square (0 or Del erase numbers). In each empty square, you may add pencilmarks for you to note the possible candidates of a square. Press ALPHA to enter and exit pencilmark mode, and press a number key (1-9) in this mode to turn that pencilmark for the square on or off. The program quits if all squares are filled in correctly or you press CLEAR.
There is a sample puzzle coded in, but if you want to change the puzzle, change GDB1 in the source file and recompile. The setup should be obvious for a puzzle, but please let me know if you have any questions.
Source file and program file available for download. Tell me your opinions so far.

I made a new game demo, this time of Sudoku!

Use the arrow keys to move the selection cursor. Press a number key (1-9) to enter a number in a square (0 or Del erase numbers). In each empty square, you may add pencilmarks for you to note the possible candidates of a square. Press ALPHA to enter and exit pencilmark mode, and press a number key (1-9) in this mode to turn that pencilmark for the square on or off. The program quits if all squares are filled in correctly or you press CLEAR.
There is a sample puzzle coded in, but if you want to change the puzzle, change GDB1 in the source file and recompile. The setup should be obvious for a puzzle, but please let me know if you have any questions.
Source file and program file available for download. Tell me your opinions so far.