Fomo3D Contracts

A countdown-based grand prize game where players burn ERC20 tokens to purchase shares and compete for the prize pool, built on BNB Smart Chain (BSC) and compatible with other EVM networks.

Technology Stack

• Blockchain: BNB Smart Chain + EVM-compatible chains
• Smart Contracts: Solidity ^0.8.33, Diamond Pattern (EIP-2535)
• Development: Foundry, OpenZeppelin Contracts

Supported Networks

• BNB Smart Chain Mainnet (Chain ID: 56)
• BNB Smart Chain Testnet (Chain ID: 97)

Contract Addresses

Network	Diamond (Proxy)
BNB Mainnet	0x062AfaBEA853178E58a038b808EDEA119fF5948b
BNB Testnet	0x22E309c31Bed932afB505308434fB774cB2B23a6

Features

• Countdown Grand Prize: Last 10 buyers split the prize pool when the timer expires (55% to #1, 5% each to #2–#10)
• Token Burn Mechanism: Players burn ERC20 tokens to purchase shares, creating deflationary pressure
• Pull-based Dividend System: Real-time earnings distribution via Earnings-Per-Share (EPS) accumulator
• Diamond Pattern (EIP-2535): Modular upgradability with 8 independent facets sharing unified storage
• Security-first Design: EOA-only restriction, reentrancy guards, emergency pause, and BNB balance tracking

Architecture

Diamond (Proxy)
├── DiamondCutFacet       — Upgrade management
├── DiamondLoupeFacet     — Contract introspection (ERC-2535)
├── OwnershipFacet        — Owner management (ERC-173)
├── PurchaseFacet         — Buy shares by burning tokens
├── ExitFacet             — Exit game / settle after round ends
├── LifecycleFacet        — End round & distribute grand prize
├── AdminFacet            — Configuration management
└── ViewFacet             — Read-only queries

All facets share state through a unified AppStorage struct via LibAppStorage.

Game Mechanics

Core Loop

Purchase shares → Countdown extends → Dividends accrue → Countdown expires → Grand prize → Next round

BNB Distribution

Pool	Default	Purpose
Injection Pool	50%	Immediately distributed in current round
Pending Pool	50%	Reserved for next round

The Injection Pool is further split:

Sub-pool	Default	Purpose
Dividend	50%	Distributed to all share holders (EPS-based)
Grand Prize	50%	Accumulated for end-of-round payout

Grand Prize Distribution

Rank	Share
#1 (last buyer)	55%
#2 ~ #10	5% each

Security

• onlyEOA — purchase, exitGame, settleUnexited restrict to EOA (msg.sender == tx.origin) to prevent flash loan and MEV attacks
• nonReentrant — All state-changing functions use reentrancy guards
• whenNotPaused — Emergency pause capability (except settleUnexited and endRoundAndDistribute)
• Pull-based withdrawals — Grand prizes credited to pendingWithdrawals, claimed separately
• BNB tracking — trackedBalance detects incoming BNB via balance diff, preventing manipulation

Build

forge build

Dependencies

• forge-std
• OpenZeppelin Contracts (IERC20, ReentrancyGuard)

License

MIT