All of this is speculation, but here is my lore theory:
Some time in the past, the unnamed planet was formed, over time several great kingdoms rose to power.
Ipsillon, with a temperate and peaceful climate
Tolbrynd, once home to now extinct giants, the mysterious power of magic crystals runs through this stormy land. The crystals also appear to have been worshiped throughout the land.
Valfross, possibly frozen by some artifact, or just naturally cold, Tolbrynd was devastated by a past war with a dragon (or possibly dragons) with many of its soldiers and even its king being frozen.
Krolmar, A desert Kingdom full of life.
It would appear that at the start of the game, these four nations are either all at war, or at least do not have a positive relationship with eachother.
One day, a strange object arrived in orbit of the planet, sending down a weapon of mass destruction to steal or destroy the unnamed world's resources and obliterate anyone or anything that stood in its way. A gray cube with fluorescent blue trim: the starting block.
The starting block first landed in Ipsillon. After passing through the islands at the base of the continent and breaking through the border to the island proper, the Queen sent her army to defeat this new invader, but they stood little chance. After this, the machine was free to pillage the remainder of the land, eventually destroying the Queen's fortress.
Next, the Block traveled to Tolbrynd, but this new land's ruler, Duke Aras was crafty. He would learn from the Queen of Ipsillon's mistakes. First the duke offered the machine gold at a border castle with great fanfare. This was apparently some sort of plea, likely a peace offering to get the machine to leave the island intact, but this was not to be. The party of unarmed knights sent to state the duke's plea were slaughtered to a man.
The duke deployed scouts to spot the machine, so that he could deploy his secret weapon: prototype bomb cows.
Yet even these proved no match for the block, and the freighters meant to ship in more prototypes were also destroyed.
The Block continued to ransack the land, destroying the food, water and shelter that the people needed to live. The Duke sent his army after the Block, but this too did not succeed. The duke even attempts to ambush the block with heavy cannons, but that is not enough to stop it from stealing or destroying most of the kingdoms valuable artifacts.
Eventually, even the duke's floating tower falls.
Then the Block travels to Valfross. It is met by a group of knights, eager for death and martyrdom. But it is the land itself that is the Block's greatest enemy, the harsh conditions providing more resistance than the Withered king's armies. Eventually the block destroys his tower stronghold as well.
The Block then prepares to destroy the final island, Krolmar, with its vaults of food and water tat must be broken into.
The survivors of the other kingdoms all begin arriving in Krolmar via ship, all rallying together under the Krolmar banner and preparing one final stand at the Empress' magnificent castle. Even one of the Duke of Tolbrynd's freighters is sent for the defense, and modified by the forces of Krolmar with an improved canon
The Machine continues to do what it does best, stealing magic, despoiling the land and shattering all resistance. Eventually reaching the final stand, meeting an allied army with soldiers from every nation, and putting a fortress to ruin.
There are no more castles to conquer.
As to why the strange entity did this, it is unknown. Perhaps it just wanted to steal things for the editor.