It's developed in Go and hence cross-plattform.
stargazer <file> [output dir (optional)]
If no output directory is given, the file is extracted to the file name minus the extension plus "_extracted" (e.g. xPackmanJr_0.105.star -> xPackmanJr_0.105_extracted).
I have also added experimental packing in an extra branch and created an issue to keep track of it.