Engineering · Base Mainnet

BUILDING PAXXEL
ON BASE

We didn't put collectibles on-chain for the sake of it. We built on Base because collectors deserve cheap settlement, transparent escrow, and randomness you can verify yourself.

Base L2 USDC Native Chainlink VRF v2.5 5 Contracts Basescan Verifiable

By Dan & Kevin · Deeridge Cards LLC · June 2026 · ← Blog

Why Base

Collectors don't need
Ethereum gas fees.

Paxxel is a game about real PSA-graded cards — not speculation on JPEGs. When someone buys a $0.63 pack, the transaction cost should be negligible. When 64 players escrow USDC for a $40 card, settlement should be fast, cheap, and auditable.

Base gave us exactly that: an Ethereum-secured L2 with sub-cent transaction costs, native USDC, and a growing ecosystem of wallets collectors already use. Coinbase, MetaMask, and Privy all support Base out of the box. That matters when your audience is card collectors, not crypto natives.

Every pack purchase, every burn round, every buyback payout settles in USDC on Base. Open Basescan. Verify it yourself.

We evaluated other chains. Solana is fast but fragmented for USDC. Ethereum mainnet is too expensive for micro-pack purchases. Base hit the sweet spot: Ethereum security, L2 economics, and USDC as the default money layer.

Architecture

Five contracts.
One game loop.

We split the system into five purpose-built contracts rather than one monolith. Each has a clear job, clear permissions, and clear audit surface. All five are live on Base mainnet today.

5
Smart contracts
64
Tokens per game
6
Burn rounds
8453
Chain ID
ContractRoleAddress
PaxxelPacks Storefront & escrow. Lists cards, sells packs, locks USDC, mints NFT + game token per pack. 0x9b69…D8C6
GameToken ERC-1155 entry tickets. 64 per card. Transferable only during trading windows. 0x3D48…937E
PaxxelNFT ERC-721 collectible per pack. On-chain SVG metadata — no IPFS dependency. 0xa0DC…E693
PaxxelGame Elimination engine. Trading windows, Chainlink VRF burns, winner selection. 0xcD36…632B
PaxxelSettlement Post-game flows: 90% buyback, marketplace escrow, physical withdrawal. 0xF807…81D2
The on-chain flow:
Admin lists card Users buy packs in USDC NFT + GameToken minted 64/64 sold, game starts VRF burns 50% per round Winner gets buyback / marketplace / physical redemption
Money Layer

USDC escrow,
not platform credits.

When you buy a pack on Paxxel, your USDC doesn't vanish into a database balance. It locks in the PaxxelPacks contract until the game resolves. Pack price is deterministic: Paxxel EV ÷ 64. A $40 card is $0.625 per pack. No hidden markup, no opaque pricing engine.

We use Circle's native USDC on Base (0x8335…2913) — the same USDC that Coinbase, bridges, and most DeFi on Base already use. Six decimals. No wrapped tokens. No proprietary stablecoin.

Before a game starts, you can cancel your reservation and get a full USDC refund on-chain. After the game starts, escrow moves to PaxxelGame and the burn rounds begin. The winner can accept a 90% buyback in USDC, list on the in-app marketplace, or redeem the physical PSA slab.

Randomness

Chainlink VRF.
Not a server roll.

The elimination game is the core of Paxxel. Once 64 packs sell, tokens get burned round by round until one holder remains. That randomness cannot come from our backend. It has to be provable.

We integrated Chainlink VRF v2.5 on Base. Each burn round requests verifiable randomness from Chainlink's oracle network. The result is published on-chain. Anyone can trace the VRF request ID, the fulfillment transaction, and exactly which token positions were eliminated.

64

Round 1

VRF selects ~50% of holders to burn. 32 remain.

32

Round 2

Another VRF burn. 16 remain. Trading window between rounds.

16

Round 3

Down to 8. Every elimination is on Basescan.

1

Winner

One token left. Settlement contract takes over.

Between burns, 2-minute trading windows open. Holders can buy and sell game tokens peer-to-peer. Transfers are enforced at the contract level — GameToken only allows movement when PaxxelGame has opened the window. No off-chain honor system.

On-Chain Metadata

NFTs that render
on Basescan.

Every pack mints a PaxxelNFT — an ERC-721 with fully on-chain SVG metadata. Player name, year, brand, grade, cert number, and token ID are encoded in the contract. View any holder's NFT on Basescan and you see the same card face we show in the app.

We deliberately avoided IPFS for core metadata. IPFS gateways go down. Pins expire. We wanted metadata that lives as long as Base does. The tradeoff is higher mint gas, but on Base that's cents — not dollars.

The NFT is separate from the game token. Your NFT is a collectible proof of purchase. Your game token is your entry in the elimination. Win the game, you get the slab. Burn your NFT separately, you can redeem a random physical card from our redemption pool.

Off-Chain, Honestly

What's on-chain vs.
what isn't.

We believe in transparency about limits, not marketing around them.

On-chainPack purchases, USDC escrow, token mints, VRF burns, buyback payouts, marketplace trades, withdrawal requests.
On-chainCard listing metadata, pack counts, game state, and all five contract addresses — verifiable on Basescan.
Off-chainPhysical cards held in an insured vault at Shoeless Joe's. Custody is real-world; ownership outcome is on-chain.
Off-chainShipping, ID verification for high-value prizes, and AMOE mail-in entry processing per sweepstakes rules.
OperatorA backend service on Railway holds OPERATOR_ROLE to start games and request VRF burns. It cannot move user USDC or mint tokens arbitrarily.
AdminCard listings require ADMIN_ROLE on PaxxelPacks. Only our deployer wallet can call listCard().

The operator is a cron job, not a black box. It watches for the GameReady event, calls startGame(), opens trading windows, and requests VRF. Every action emits an event you can audit. We're building toward more decentralization over time, but we'd rather be honest about the current architecture than pretend it's fully trustless.

The Stack

From wallet to
graded card.

Frontend — Next.js on Vercel

React app at paxxel.io. Privy handles wallet creation and Google OAuth. Users get an embedded wallet on Base automatically — no seed phrase homework on day one.

Backend — Node on Railway

Game orchestrator, admin APIs for card listing, PSA image fetching, Supabase sync, and Discord webhooks for drop announcements. The backend drives the game state machine; the contracts enforce the rules.

Contracts — Solidity on Base

Hardhat for development and deployment. OpenZeppelin for access control and reentrancy guards. Chainlink VRF v2.5 for randomness. Deployed to Base mainnet (chain ID 8453) with verified source on Basescan.

Data — Supabase

Card listings, game history, waitlist, and image storage. On-chain state is source of truth for money and tokens; Supabase is the read layer for the UI. We sync from chain events and expose a public listings API.

Collectors shouldn't need to understand any of this to play. But if they want to verify a burn, trace escrow, or inspect a listing transaction — every piece is on Basescan.
Compliance

Built for sweepstakes
law, not loopholes.

Paxxel is operated by Deeridge Cards LLC, a licensed Fanatics and Panini dealer based in Cincinnati, Ohio. The game structure — known card, fixed entries, free AMOE mail-in alternative, geographic restrictions — is designed around sweepstakes compliance, not casino logic.

Base is the settlement layer. Compliance is the business layer. Both matter.

What's Next

Base is the foundation.
Not the ceiling.

We're live with five contracts, five card drops, and a weekly game cadence. Short term: more drops, faster orchestration, Coinflow fiat on-ramps so collectors can fund with card and ACH — not just crypto USDC.

Medium term: a fuller secondary marketplace, subgraph indexing for real-time holder tracking, and multi-sig admin for contract upgrades. Long term: we're watching how Base, Coinbase, and the broader on-chain collectibles space evolve — and building Paxxel to be the most transparent high-stakes card game on the chain.

If you're a builder, auditor, or collector who wants to dig into the contracts — they're all verified on Basescan. DM us on X or join Discord. We built this in the open because the whole point is verifiability.

Play the Game

SEE IT ON BASE.

Five drops live. Weekly burn games. Every result verifiable on Basescan.