X1City is a unified, persistent open world built on the X1 Blockchain and rendered in Unreal Engine 5. It is being designed and built by a single founder — X1 Brains — on top of a working DeFi stack that already ships on X1 mainnet today. The goal is not to be a federation of separate projects. It is to be one coherent city, with one architectural vision, opened up afterward to other projects via property NFTs they can rent or buy.
The build sequence is deliberate: architecture first, properties next, then the agent layer. Buildings, streets, lighting, and terminals are being placed before any property NFTs go on sale. This avoids selling promises and instead anchors every claim in something visible. The financial backbone — Lab Work (LB Mint), the LB NFT Marketplace, LP Pairing, Brains Farm, the Incinerator, the Rewards Hub, Cyberdyne Unlimited, and the portfolio tracker — is already live at x1brains.io.
This document is v0.2. It supersedes prior drafts that described X1City as a three-builder federation. As of April 2026, X1City is a solo build under X1 Brains, with the original co-conceivers acknowledged in the origin story but no longer involved in development.
The city itself is the asset. Every parcel is land. Every building is a property. Every protocol that moves in is a tenant. As the city grows, the value of what's already inside it grows with it. DeFi runs underneath. Agents come later. The architecture is the foundation of all of it.
The idea for X1City was sparked in a Telegram conversation between a few X1 builders earlier in 2026. The shared image was a Monopoly board. The question was: what if the blockchain itself was the city — and what if instead of competing for the same users, builders could each contribute something to a single, unified open world?
The conversation seeded the concept. The build, however, is solo. Two of the original co-conceivers stepped away from X1 development as the regulatory landscape shifted in early 2026. X1 Brains carries the work forward: designing the city, modeling it in Unreal Engine 5, and shipping the DeFi stack underneath at x1brains.io. The Telegram conversation gets credit for the spark. The execution is one builder's work.
The domain x1.city was secured. The first buildings were placed in Unreal Engine 5. The architecture pass — exteriors, streets, lighting, terminals — is the current focus. Interiors, properties, and on-chain interactables are next.
"Build the city tight. Place the buildings. Light it up. Then open the gates and let other projects move in. The economy of X1City is the city itself."
— X1 Brains · Build NotesThe deliberate choice from day one: keep it underground while the architecture comes together. Don't announce a concept — have something real before opening the gates. v0.2 of this whitepaper marks the point where the solo-build path is the public path.
X1City is being built with one design principle running through everything: architecture first. Buildings, streets, lighting, and the visible structure of the city come before properties go on sale and before agents come online. The goal is to build something real and let the economy assemble around it — not the reverse.
"One builder. One city. Build it tight. Ship what's real. Open the gates when the architecture is done."
— X1 Brains · Build NotesMost blockchain metaverses sell parcels before there's a world to put them in. X1City inverts that: the city is being designed, modeled, and lit first. Once the architecture pass is complete, properties and parcels become NFTs that other projects can rent or buy to host their dApps inside the world. The order matters — and the order is honest.
X1City does not sell what doesn't exist yet. The land NFTs, the property deeds, and the NPC agent layer are all real future steps — but each ships when the underlying work is in place. The DeFi stack is already on mainnet. The architecture pass is in progress. Properties open after the architecture is set. The gates open when the city is real enough to walk through.
Most blockchain worlds launch a marketplace before there's anything to put in it. They sell parcels backed by promises of what the world will eventually look like, and the gap between the rendering and the reality kills momentum. X1City is being built in the opposite order.
| Phase | What Ships | Why |
|---|---|---|
| Phase 0 — Already Live | x1brains.io: portfolio tracker, LB Mint, LB NFT Marketplace, Incinerator, Rewards Hub, Cyberdyne, LP Pairing, Brains Farm | Working DeFi stack on X1 mainnet. Anchors every claim in the whitepaper. |
| Phase 1 — Architecture | UE5 city: building exteriors, streets, lighting, terminals, signage. Concept-to-blockout pass complete; visual polish ongoing. | The city has to exist before parcels can be sold honestly. |
| Phase 2 — Property NFTs | Land parcels and building deeds as NFTs. Tenant onboarding for other projects. Lease and ownership mechanics. | Once the city is real, the economic primitive becomes the city itself. |
| Phase 3 — NPC Agents | Claude API integration as the city's voice. NPC characters tied to buildings and districts, aware of live on-chain state. | NPCs move into a city that already works. |
The architecture-first approach has three properties that matter. First, every claim in this whitepaper is backed by something concrete — either already shipping (the DeFi stack) or visibly under construction (the city itself). Second, when properties go on sale, buyers can walk through what they're buying instead of trusting a roadmap. Third, the order matches how real cities form: skylines come before zoning maps come before tenants come before commerce.
If a feature is on the roadmap, the underlying work has to be visible before the feature is sold. Parcels open after the architecture pass. NPC agents come online after Claude integration is real. The whitepaper shows the order — the build follows it.
Phase 1 of X1City is a single unified open world built in Unreal Engine 5, currently in its architecture pass — exteriors placed, streets and lighting set, no interiors yet. Rather than a federation of separate districts, the city is being designed as one cohesive environment. Different zones have different purposes, but they're all part of the same world and built by the same hand.
As the city expands, additional zones can be opened — themed districts for gaming, marketplaces, or specific tenant communities. Brains will design and build the architecture; tenant projects will occupy and operate the protocols inside. The city itself remains a unified work, designed and maintained by one builder.
X1City sits on top of a working DeFi stack already deployed on X1 mainnet. These are not roadmap items — they ship today at x1brains.io and they are the financial backbone the city is being built around.
Lab Work is a deflationary minting protocol on X1. Users burn BRAINS tokens and pay an XNT fee to mint LB — a Token-2022 asset capped at 100,000 units. The pricing tiers up as supply increases. The Xenblocks Amplifier lets holders of XNM, XUNI, and XBLK earn bonus LB on each mint. 100% of BRAINS used in mints is permanently burned. LB itself carries a small Token-2022 transfer fee that flows to the treasury. Every parameter — tier prices, supply cap, transfer fees — is enforced by the on-chain program.
The Brains LP Pairing Marketplace solves a problem every token launch faces: to create a trading pool, you need two assets, but most builders only have one. The protocol enables trustless peer-to-peer liquidity pool creation directly on XDEX. A lister posts what they want to pair and at what value. A matcher brings the complementary asset. The pool spawns automatically with neither side having to trust the other.
The newly deployed Brains Farm pairs with the LP Pairing Marketplace. Stake LP tokens (BRAINS/XNT or LB/XNT) and earn rewards across three lock tiers — 30 days at 2× weight, 90 days at 4×, 365 days at 8×. A 3-day grace period protects against accidental commits. Past grace, an early-exit penalty applies, with discounts for LB holders. Rewards are issued via a continuous accumulator, claimable every 24 hours after the grace period. Forfeited rewards from early exits stay in the vault and boost APR for committed stakers.
The x1brains.io hub itself includes the portfolio tracker (XNT, SPL tokens, Token-2022 assets, XenBlocks holdings), the LB NFT Marketplace with list/buy/cancel/boost functions, the Incinerator (burn BRAINS → earn LB Points → ascend the leaderboard), the Rewards Hub with weekly prize vaults, and Cyberdyne Unlimited — the X1 citizen registry with tier rankings and the live leaderboard.
Every building in the Financial Quarter has a real on-chain analog. When you walk into the Lab Work building in UE5, you are looking at the same protocol that's already minting LB on mainnet. The architecture is just the visual surface — the engine is already turning underneath.
Once the architecture pass is complete, X1City opens its property layer. Land parcels and building deeds become NFTs. Citizens can own pieces of the city. Tenant projects can rent or buy buildings to operate from inside the world. This is the primary economic primitive of X1City — not a token economy bolted onto a 3D environment, but the city itself functioning as the asset.
| For Citizens | For Tenant Projects |
|---|---|
| Own a city plot — Land NFT | Rent a building — run dApps inside |
| Hold a building deed — Property NFT | Buy a parcel — permanent address in the city |
| Tokenize LP positions — Liquidity NFT | Operate a storefront with in-world foot traffic |
| Lease or sell on the open market | Apply for branded zones (by arrangement) |
| Footprint scales with holdings | Direct exposure to X1City citizens |
The economic logic is straightforward: as more tenant projects move in, the city becomes more useful. As the city becomes more useful, it draws more citizens. As more citizens arrive, the value of every property inside it appreciates — for both early citizens and early tenants. The city itself is the network effect. The longer it runs, the denser the value gets.
Tenant projects looking to occupy a building or branded zone in X1City will go through a structured onboarding once the property layer goes live. The goal is to keep the city coherent — not every zone is open to every project, and the architectural integrity of the city is treated as a long-term asset. Details on the tenant program will be published as Phase 2 approaches.
Every meaningful object inside X1City — land, buildings, LP positions, items — is an NFT, but not a static one. Smart metadata makes them dynamic, composable, and tied to real city activity. The more land you hold, the more buildable footprint you have. Buildings can host protocols. LP positions can be sold or transferred as a single asset.
| Asset Type | Mechanics | Status |
|---|---|---|
| Land Parcel NFT | Ownership of city blocks. More land = more buildable space for protocols, games, and storefronts. | Phase 2 — opens after architecture pass |
| Building Deed NFT | Ownership of specific buildings. Can be leased to tenants, upgraded, or used to host protocols. | Phase 2 — alongside parcel sale |
| Liquidity NFT | Tokenized LP positions from the Brains LP Pairing Protocol. Entire pool positions transferable as one asset. | Live now — via x1brains.io |
| LB (Lab Work) | Token-2022 deflationary asset, capped at 100,000. Tier-priced. Burns BRAINS on every mint. | Live on X1 mainnet |
| Item NFT | In-world items used in games, tasks, and commerce. Smart metadata enables item evolution. | Long-term |
The longer-term vision is to develop AMM-style pools specifically for NFTs — bringing the same liquid market infrastructure to in-world assets that already exists for tokens. The LP Pairing Protocol was built with this in mind: the same trustless pairing logic can be extended from token-token pools to NFT-token pools as the marketplace matures.
The agent layer in X1City is built into the city itself. Agents are not a service citizens register for — they are characters that populate the world. Walk up to a shopkeeper, a building operator, a city guide, or a district character, and that NPC responds in plain language with awareness of live on-chain state. The city is alive because the city talks back.
The first AI model X1City integrates with is Anthropic's Claude, accessed via the standard Claude API. Claude is chosen because of its strength in nuanced language and multi-turn dialogue — what NPCs need when responding to citizens who walk up to them and ask anything from "what's the LP listing today" to "how do I find the Lab Work building." Each NPC is given a role, a location, and a connection to the on-chain data relevant to its role.
NPC agents ship after the city architecture is in place because there's no point giving voices to buildings that don't exist yet. The buildings get placed first. The terminals and signage go up. Lighting and atmosphere come next. Then NPCs are added — one by one, tied to the buildings they live in. The result: when a citizen walks into the LB Marketplace for the first time, the clerk is already there, already aware of the live order book, already knows how to help.
The NPC agent layer is intentionally smaller in scope than what earlier drafts described — no user-registered agent IDs, no behavioral scoring, no agent council governance. Just the city populated with helpful, on-chain-aware characters powered by Claude. That's a build a solo founder can ship. The bigger ideas can come later if the city earns them.
X1City is built in phases that match the architecture-first principle. Each phase opens once the underlying work is in place. No phase ships ahead of its foundation. The current state: Phase 0 (DeFi stack) is live; Phase 1 (architecture pass) is in active construction.
| Phase | Scope | Status |
|---|---|---|
| Phase 0 — DeFi Engine | x1brains.io: portfolio tracker, Lab Work / LB Mint, LB NFT Marketplace, Incinerator, Rewards Hub, Cyberdyne Unlimited, LP Pairing Marketplace, Brains Farm | Live on X1 Mainnet |
| Phase 1 — Architecture | UE5 city — exteriors, streets, lighting, terminals, signage. Concept-to-blockout pass complete; visual polish ongoing. No interiors yet. | In Progress |
| Phase 2 — Property Layer | Land parcel and building deed NFTs. Tenant onboarding for other projects. Lease and ownership mechanics. Property marketplace. | Design |
| Phase 3 — City Hall | Central hub interior. Live dashboards. Network terminals. Cross-protocol portal. City directory as more tenants move in. | Planned |
| Phase 4 — NPC Agents | Claude API integration as the city's voice. NPC characters in major buildings — guides, operators, shopkeepers — aware of live on-chain state. | Long-Term |
| Phase 5 — Expansion | Additional zones, themed districts, mobile integration, marketplace evolution. Scope determined by what the city actually needs at that point. | Vision |
As of 2026, the space is active with AI, blockchain, and metaverse experiments — but no project has shipped the convergence X1City is building toward, particularly with the architecture-first sequencing. Most existing projects hit one or two of the core pillars. X1City's distinguishing feature is that the DeFi engine is already running before the city even launches its property layer.
| Project | Strength | Gap vs X1City |
|---|---|---|
| Virtuals Protocol | Agent tokenization, on-chain agent identity, monetization | No persistent 3D world, no UE5 architecture, no integrated DeFi stack |
| Decentraland | Virtual land economy, user events, established community | Lightweight AI, no agent companions, weak DeFi integration, ports rather than native chain build |
| The Sandbox | User-created content, large ecosystem, partnerships | No native AI agent layer, centralized elements, no on-chain DeFi engine running underneath |
| ElizaOS / ai16z | Autonomous on-chain agents, wallet capabilities, DeFi execution | No 3D world, no visual environment, no property economy |
The pieces — UE5 for visuals, Token-2022 for asset design, Anchor for smart contracts, Claude API for reasoning — have all matured enough that this is now buildable by a single technically capable founder. X1City is positioning to be the first to ship them in the right order.
X1City is built by a single founder. The idea was sparked in a Telegram conversation with a few X1 builders earlier in 2026, but the design and build are solo work. The other co-conceivers stepped away from X1 development as the regulatory landscape shifted; X1 Brains carries the work forward.
X1 Brains is the creator of x1brains.io, the most complete hub on the X1 Blockchain. Its modules include the portfolio tracker (XNT, SPL, Token-2022, XenBlocks), the LB NFT Marketplace (scan, list, buy, mint LB tokens), the first Proof of Burn token on X1 (Lab Work), the Incinerator burn engine that lets users burn BRAINS to earn LB Points and ascend the leaderboard, the Rewards Hub with weekly prize vaults and Lab Work submissions, Cyberdyne Unlimited — the Imperial Citizen Registry for looking up X1 citizens by username or wallet — and the Brains LP Pairing Marketplace, the first trustless LP pair creation platform on X1. Most recently: the Brains Farm staking program, deployed and live.
Recognized as #3 Top Builder on X1 and Cyberdyne Approved. Now designing and building X1City in Unreal Engine 5, with the x1.city domain secured. The full stack — DeFi programs in Anchor/Rust, frontend in React/TypeScript, city in UE5 — is being built and maintained by one shop.
X1City is not finished. The whitepaper you're reading is v0.2 — a snapshot of where the city is right now and where it's heading. It will be revised again as Phase 1 architecture wraps and Phase 2 properties open. This is a living document because the project is a living build.
The path is honest about itself: the DeFi engine is already shipping at x1brains.io; the city is in its architecture pass; properties open after the architecture is real; agents come after that. Each step proves the next one is buildable. No promises sold ahead of work done.
If you found this early — you're early. The DeFi stack is live to use today. The city renders are coming as the architecture pass advances. The property layer opens when the city is real enough to walk through. That's the deal.
"Build it tight. Place the buildings. Light it up. Then open the gates and let other projects move in. The economy of X1City is the city itself."
— X1 Brains · Build NotesThe DeFi engine is on at x1brains.io. The city is being built at x1.city. When the gates open, the people who showed up early will already know how to walk through.
x1.city · X1 Blockchain · Unreal Engine 5 · Anchor · Token-2022
X1CITY WHITEPAPER v0.2 · LIVING DOCUMENT · APRIL 2026 · x1.city · X1 BLOCKCHAIN · UNREAL ENGINE 5
BUILT BY X1 BRAINS · ARCHITECTURE FIRST