Another question: Is this game story worth playing?
The easiest way to explain the development plan is to view it as a book, which releases one chapter at a time. As such we don't have the ending yet, but what we do have is more or less complete.
Sure due to being a branching visual novel with optional parts to it, it's not as simple as a story from A to B. There are paths, which quickly ends with "will be added in a later update", but that's less of an issue than it sounds like. If you like it, then you like it in the current state and if you don't, waiting for it to be finished won't help because it just isn't the game for you.
Having said that, once in a while old parts are updated. This is mainly fixes such as replacing early graphics as later graphics reveal higher quality due to experience. Bugfixes are also added whenever a bug shows up, through I will say that generally the number of bugs is quite low. To my knowledge, there aren't any known bugs at the moment.