I don't know anything about that game but it seems to be a guide https://github.com/pioneerspacesim/pioneer/blob/master/COMPILING.txt
in how to compile it and run it, in the link you provided https://pioneerspacesim.net/page/download/
To do it, first you need to install system.devel
component
run this in the terminal:
sudo eopkg it -c system.devel
Wen finished, you are good to go and then you can start with the guide.
https://github.com/pioneerspacesim/pioneer/blob/master/COMPILING.txt
I hope that could help you. 😀