The setting of Project Rabbit is the one part of the game that has been described in real detail, and it is built on a single image: a world that has come apart at the seams, and something sealed inside it.
The official premise is that the forces of the dimensions collapsed, and fragments from different realms became entangled into a single world. Where those pieces overlap, in the cracks between them, the Abyss of Time came into being. The store copy describes it as a distorted world sealed by the Blood Queen — Reina de Sangre in the original Spanish-language phrasing that appears in some regional store listings.
Inside the Abyss, things wander that are neither alive nor dead, trapped in an endless loop of time. That is the mechanical seed for everything else: the enemies are not a bestiary of animals and soldiers but remnants of a place that has stopped working properly, and the resources you extract are the residue of a world that has been running on the same broken loop for a very long time.
The second half of the setting is the Barrier of Light — a diminishing ward under which the survivors have built their last sanctuary. The barrier is failing, which is the reason anyone has to go back into the Abyss at all. Your objective, in the store copy's own framing, is to survive with Alice "from the madness that devours the Abyss of Time", to resist the corruption of both madness and the Blood Queen, and to restore the balance of the world.
The Abyss is divided into five biomes, each with its own unique guardian. That much is confirmed. What is not confirmed is any of their names — the official material gives the count and the structure, and the location names that circulate in coverage ("castle", "garden", "clock tower") are descriptive shorthand from press writers rather than official geography. This wiki will list them as they are announced.
Also confirmed is the presence of hidden hiding places scattered through the Abyss, and of other survivors encountered in the field — players who may help you, or may not. The October and November trailers show a specific kind of encounter: figures that are unmistakably human, standing in the ruins, that you have to read correctly before you decide what to do about them.
The visual identity is the part of Project Rabbit that has generated the most attention, and it is worth describing precisely rather than as "an Asian take on Alice in Wonderland".
One important caveat on the fiction: the official store copy states the game is "enriched by a proven Webtoon IP", but that Webtoon has not been named. Until it is, treat the relationship between Project Rabbit and any specific published work as unconfirmed, and treat the Alice in Wonderland elements as the confirmed layer.