Lostbelts

Lostbelts are a concept introduced in the mobile game Fate/Grand Order. They represent alternate timelines or parallel worlds that have been erased or "pruned" from the main human history by the action of the world itself. These pruned timelines are considered divergent and ultimately unsustainable, leading to their inevitable removal.

Unlike normal alternate histories, Lostbelts are characterized by a specific event or condition that prevented them from developing into the true human history. These conditions often involve a drastic divergence from the established course of events, leading to a unique and often grim reality. The world deems these timelines to be "lost" because they cannot reach the established level of human progress or survival.

The primary antagonists of the Lostbelt arc are the Crypters, mages who have allied with the alien invaders known as the Alien God. The Crypters, along with their summoned Heroic Spirits, seek to preserve their respective Lostbelts by overwriting or replacing the "pruned" main human history with their own. This objective inherently involves the destruction of the established human history and the lives within it.

The protagonists of Fate/Grand Order, the Chaldea Security Organization, embark on a mission to travel to these Lostbelts and dismantle the Crypters' plans. Their goal is to restore the true human history and prevent the complete erasure of existence. Each Lostbelt presents a unique challenge, with distinct environments, societies, and inhabitants shaped by their divergent histories. The exploration of these worlds raises questions about the nature of history, survival, and the definition of humanity.