I finished Skyborn, and the finale went down exactly as I expected - you had a mission in the palace, and then after you defeat the villain you've been opposing for the whole game, it turns out there is there is some random alternate dimension of evil that you have to shut down to save the world. Pretty standard jrpg stuff.
Now that I've played through the whole thing, I have to say that Skyborn is pretty much the paradigmatic rpg. And while you could interpret that to mean that it's unoriginal and cliched, I actually find something admirable in its craft. Like, when you build a ship in a bottle, you're not really trying to come up with an innovative new ship design because the whole point is that at the end of this painstaking and delicate process, you wind up with something that looks like a ship.
If you view rpgmaker as a hobby kit, than Skyborn is kind of the ideal game. Someone used the hobby kit to make a thing that looks exactly like the sort of thing that was popular enough to inspire the creation of a hobby kit. Understand that it is without a trace of irony that I say I admire the creator's restraint in not attempting to reinvent the wheel.
I know from bitter personal experience that it is all to easy for a moderately clever person to get one good idea and then crawl so far up their own ass that they don't realize, until too late, that they don't know how to get the fundamentals right. Skyborn doesn't have that problem. It's pretty much all fundamentals, but within those constraints, it is rock solid.
I suppose, if I had paid money for this game, I might be upset that it didn't have anything particularly challenging or surprising about it (and I wouldn't recommend buying it at full price), but as a pure experience, divorced from any sort of financial interest, I found its familiarity comforting.
From here, I'll probably go back and beat the optional bosses (I think I have a save from before the point of no return, but I'll have to double check). That should take a couple of hours. Then, if I still have time left, I'll start over on hard mode, and see if the game is fair on the increased difficulty level.