gnome-sudoku software package provides Sudoku puzzle game for GNOME, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnome-sudoku
gnome-sudoku is installed in your system.
Make ensure the gnome-sudoku package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnome-sudoku *
You will get with gnome-sudoku package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Games |
| Package | gnome-sudoku |
| Version | 1:3.22.0-1 |
| Description | Sudoku puzzle game for GNOME |
| Sub Section | Games |