I think this was a ARCADE only title, to learn more about it please visit @ http://www.geocities.com/arcadeclassics.geo/STARCASTLE.html
If you goto http://www.renate-hat.onlinehome.de/tillorg/a128/dcastle.html
you can find out information and download a demo (self booting version) for the SEGA DREAMCAST!. check it out.