WHAT IS SATOSHI WORLD? Satoshi World is a pixel-art platform adventure and the first prototype built with the N-CARTS project. N-CARTS is an NFT digital-cartridge architecture that integrates program, ownership and memory into one logical unit. Each cartridge preserves a verifiable identity, runs its content and maintains portable state attached to its history. WHAT THE CARTRIDGE CONTAINS The cartridge contains a self-contained HTML document with the engine, rules, maps, graphics, sound and N-CARTS protocol version. The browser interprets that document as a complete program. Essential resources travel inside the content and do not depend on a proprietary gaming platform. The base payload works like the ROM in a classic cartridge: it defines the work, its logic and its technical identity. Its hash verifies that the executed bytes are exactly the bytes recorded on-chain. INSCRIPTION, IDENTITY AND OWNERSHIP The payload is inscribed on the BSV blockchain and associated with one satoshi. The first output that identifies it is its origin; the current outpoint locates the unspent output representing present ownership. The wallet controlling that outpoint controls the cartridge. A transfer moves the satoshi and its identity to a new output: the owner wallet changes without separating the game, its provenance or its verifiable history. The origin remains the stable reference and the outpoint reflects its current location. LOADING AND EXECUTION A compatible browser or reader receives the origin or outpoint, resolves the ownership chain, retrieves the bytes recorded on BSV, verifies their hash and opens the HTML. The engine runs locally on the player's device; BSV preserves the verifiable source from which the cartridge is recovered. The cartridge needs neither a store nor a private game server to exist. It needs access to BSV—through a node, indexer or compatible reader—and an environment capable of interpreting its web format. PORTABLE SAVE AND HISTORY The base payload remains immutable. The game evolves through an append-only chain of signed state records. Each record references the cartridge origin, protocol version, previous state hash and new state: progress, routes, records, achievements, inventory and results. The reader reconstructs the game by following those links and accepts the latest valid record authorized by the owner wallet as the current save. Earlier history is not overwritten: it remains ordered, verifiable and protected from silent alteration. When the cartridge changes owner, its payload and history remain linked to the same origin. The new wallet controls the outpoint and signs later states; complete provenance stays attached to the asset. IDENTITY AND SESSION CENTER The identity icon brings together the session, network, NFT status, owner wallet, origin, outpoint and save location. Connecting a wallet starts a signed proof of control; it never gives the private key to the game. Save and exit serializes the state, links the previous record, requests the wallet signature and records the new continuation point. Sign out removes local session authorization without deleting the cartridge or its history. COMPATIBILITY, MULTIPLAYER AND TRADING Each cartridge declares its N-CARTS version and capabilities. Two compatible NFTs compare those declarations, verify origins, owners and signatures, and open a shared session governed by rules known to both. Co-op play, battles and trades are expressed as signed messages identifying the session, participants, action and order. Accepted events form a verifiable record; results and state changes link into each cartridge's BSV history. A creature game, for example, transfers a creature through an operation signed by its owners and recognized by both compatible cartridges. SECURITY AND INTEGRITY The seed and private keys remain inside the wallet. The game requests specific signatures and receives only the signature and public data needed to verify authorization. Each reader verifies payload, origin, outpoint, state chain, protocol version and signature before accepting ownership, saves or messages. This separation keeps the base work immutable, allows its memory to evolve and preserves complete traceability without giving the game the credentials that control the NFT.