There are three kingdoms, each with a stone allowing its ruler control over the land, the sea, or the sky. Legends tell of a king who united the three stones for control over the entire world. Meanwhile, our brother has just been crowned the ruler of the kingdom of the land, and given its stone of power. Then we find the crown of the old king of the world, and now we must unite the three stones again to become the new king of the world.
This story is presented much like a children's story or fairy tale, with very simple language and characters that seem flat by stylistic choice rather than by any lack of ability. (Although our hero's grousing after parting with Kari does seem a little clumsy. People generally don't actually say "Grr!" in real life ... that's only done in comic books because they don't have speech tags to say that someone "growled".)
Gameplay is a fairly simple matter of choices. One section plays out a bit like a management sim, and another like a standard IF exploration game. In both cases, though, it's pretty light and easy to manage.
I get the impression that something a bit deeper and perhaps a little subversive was intended here, as though the quest to claim the throne was meant to open our eyes to the idea that the original legend was in fact sugar-coating a great evil. But that's not quite how the ending plays out. Perhaps the consequences are, to some degree, realistic: accepting the crown in the end does open the way to "great and terrible things", and renouncing it won't do anything for hostilities between the three kingdoms. It's hard to say what the aim here really is.
I think this might be steel-cut oats with a dollop of honey, followed by a glass of milk. Sweet enough for kids, but with something grown-up at the bottom ... kind of a bland finish.