To install gncgym and all of its dependencies, clone the repository and navigate to the folder, and then use pip install.
git clone https://github.com/haakonrob/gncgym
cd gncgym
pip install -e .
This installs gncgym as an "editable" library using links. If you don't need to edit the files, and just want to use the library, just use the following instead of the last line.
pip install .
This will also create a startup script that allows you to the library from the command line.
After installation, type the following in a terminal to start an example scenario where you can control the vessel using the arrow keys.
gncgym play