I vaguely remember something about this, but I forget the exact details.

The original is free (with or without the adult content). However acadamy and the sequel costs. If the original is open source, then its probably to be found on Sekai project site.

Sunrider: Mask of Arcadius (made up of the first two parts of Sunrider, First Arrival and Mask of Arcadius) is freeware, the following definition is taken from the original Kickstarter page:

- Obviously, Love in Space has an absolutely zero DRM stance.
- You are free to modify, translate, mod, and/or expand upon Sunrider is any manner you choose, so long as you do not charge other people money for any of Sunrider's assets.
- Love in Space gives you the right to use Sunrider in any other manner you want, with the only condition being you do not charge other people money for any part of Sunrider.


Sunrider Academy and Sunrider Liberation Day however are not freeware just to clarify.