balder2d software package provides A 2D shooter in zero gravity, 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 balder2d
balder2d is installed in your system.
Make ensure the balder2d package were installed using the commands given below,
$ sudo dpkg-query -l | grep balder2d *
You will get with balder2d package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Games |
| Package | balder2d |
| Version | 1.0-2 |
| Description | A 2D shooter in zero gravity |
| Sub Section | Games |