The world of TowerFall is a setting rich with history and lore ranging from centuries in the past to a future that occurs after the events seen in the game. Below details some of the lore as it has arisen from official sources including the game's minimal narrative, developer interviews and the official Tumblr devlog posts. More information regarding the archers and towers appearing in the game can found in their respective main pages.
TowerFall

World map of TowerFall
The world of TowerFall comprises many areas whose inhabitants live under the rule of Kings. The main continent features a northern arctic zone, several mountain range and temperate forested areas and a vast desert in the east. The sparse southern continent is largely uninhabited though features several monuments and landmarks important to the history of TowerFall.
Creation
It is not clear when or how the world of TowerFall was first created, but it is speculated that the certain deities and the location of TowerForge were involved.
Ascension
The Ascension tower lies in ruins at the beginning of the game. The reason for its creation and the events surrounding its destruction are unknown however is appears to be of pivotal importance. Sunken City, Moonstone and TowerForge are all of importance to the history of TowerFall and are all related to the restoration of the Ascension tower. Once restored, the tower itself becomes the stage of the final battle to save TowerFall concluding with the banishment of all remaining demonic forces.
Kings
TowerFall has not always been ruled by royal families, though it appears that recent history has seen the rise and fall of several monarchies with resulting wars for power and control of the lands. The current King of TowerFall took possession of the throne after a victorious battle, aided by the combat prowess of the Red Archer. The extent of his rule appears to cover the western end of the main continent of TowerFall. In the eastern end lies Mirage which has its own ruling monarchy of which the Pink Archer is an heir.
Deities

An effigy of the Moon Goddess
Moon Goddess
The Moon Goddess appear to be the deity of greatest importance to the people of TowerFall. Her power and the light that is reflected by the moon is said to have a calming and restorative effect.
Sun God
The Sun God is referenced in the theme music of Mirage and is perhaps the deity most worshiped by the Mirage kingdom. His relation to the Moon Goddess is unclear, though the two may have played a role in the creation of TowerFall.
The Order
see main page: The Order
The Order is an ageless order of protectors whom made a pact with the Moon Goddess centuries ago to help maintain the balance of power on a cosmic scale. They stood together utilizing power granted to them by the Moon Goddess to defend TowerFall from demonic forces, though past events fractured their bond and now one stands alone as the Last of the Order.
Dark World
The Dark World is a demonic counterpart to the world of TowerFall. From what little that has been seen of the Dark World, it appears that its geography matches almost identically with that of TowerFall. Its origin and relation to TowerFall is not entirely clear, though the demonic forces that inhabit it have posed a long standing threat to the inhabitants of TowerFall, able to invade the various lands by way of Dark Portals. Anyone who enters the Dark World without pure intentions becomes corrupted by its demonic energy.
Demons
The demons of the Dark World, whose number are unknown, seem to possess a great desire to bring ruin to TowerFall. When the Purple Archer fell victim to the Dark World she became a vessel for demonic possession. With the combined power of the Moon Goddess bestowed on the Purple Archer as a member of the Order, the demon by which she is possessed made great strides spreading corruption and chaos across TowerFall. When the heroes of TowerFall entered the Dark World seeking vengeance, the Purple Archer stood as leader of the demonic forces.
Dark Portals
The Dark Portals are the means by which the demonic forces of the Dark World enter TowerFall. Conversely, transit from TowerFall to the Dark World is also facilitated by the Dark Portals. The Red Archer is known to have sailed her entire ship, the Amaranth through a Dark Portal seeking adventure on the other side, and the heroes of TowerFall were also able to enter by way of a Dark Portal. It is however not clear if these portals were purposefully created or discovered by other means.