Well, this is a Twine/Harlowe game so basically it's just html/css with JavaCode. Which means, this is absolutely non-OS-specific as it is. All you need is just a decent web browser with a good JavaScript engine. All modern browsers, regardless of OS, should be able to run it. In fact, the current version is already OS-independent as it is only an html file (with all the JavaScript code embedded).
If adastra one day should include art (not from external sources as it is now, which, btw, is prone to break in the future), the question of packaging might arise. But in general just a sub-folder with content sitting just beside the main html file would be enough and should work as well for all OS/browser combinations.