From publisher blurb:
HC SVNT DRACONES: Core Extended brings your HSD game up to the next level. Contained within this book are over two dozen new playable character options, new surgeries, new focus abilities and implants, additional playable races beyond Vectors, and lore detail to help players and Guides alike get a better grip on their world. All these features can slot into existing HSD games to provide greater depth and variety to your gameplay.
Core:Extended is an expansion to the HC SVNT DRACONES role playing game, and as such you will require the core rulebook to play. Rules included in C:E can be applied to existing campaigns immediately with no need to make new characters (though with all the new options, you may want to just to be someone new!) C:E also includes the C:E combat addendum, which changes the way combat works in HSD. That particular document is FREE, you don't need to buy this book to get it. It is now included in the HSD core rulebook .pdf and can be downloaded separately from the hsdroleplayinggame website for immediate inclusion in your games.