Tropex

Real-time multiplayer economic simulation and card trading game — bet on creators, ride the curve, beat the market.

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Overview

Tropex is a real-time multiplayer trading platform where players buy and sell creator cards whose prices move along a sigmoid bonding curve based on live market activity. Think of it as a stock market, but the assets are people — and the price is determined by math, not mood.

Built as a full-stack monorepo with a focus on real-time performance, provably fair pricing, and a clean developer experience.

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Tech Stack

Backend

Layer	Tech
Runtime	Bun
Framework	Express 5
Language	TypeScript
ORM	Prisma
Database	Neon (PostgreSQL)
Cache / Pub-Sub	Upstash Redis
Auth	Supabase Auth
Realtime	Supabase Realtime

Frontend

Layer	Tech
Framework	Next.js 15 (App Router)
Styling	Tailwind CSS
Components	shadcn/ui
Charts	Recharts
Language	TypeScript

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Monorepo Structure

tropex/
├── apps/
│   ├── server/          # Express 5 backend (Bun)
│   └── web/             # Next.js 15 frontend
├── packages/
│   └── db/              # Prisma schema + client (shared)
└── package.json

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Features (V1 — Backend Complete)

✅ Authentication

• Supabase Auth integration (email/password)
• JWT verification middleware on all protected routes
• Session handling with Supabase client

✅ Cards API

• Full CRUD for creator cards
• Card metadata: name, category, description, image
• Seeded database with initial card set

✅ Sigmoid Bonding Curve Pricing Engine

• Price determined by supply via a sigmoid function — early buyers get low prices, late buyers pay a premium
• Built with decimal.js for precision arithmetic — no floating point drift
• Price recalculated on every trade

✅ Trade API

• Buy and sell endpoints with atomic wallet + holding updates
• Trade validation: balance checks, holding checks, supply checks
• Full trade history stored per user

✅ Wallet API

• Per-user wallet with balance tracking
• Debit/credit on trade execution
• Transaction log

✅ Portfolio API

• Aggregated holdings per user
• Current value computed from live card prices
• P&L calculation (cost basis vs. current value)

✅ Leaderboard API

• Ranked by portfolio value
• Supports pagination

✅ Database Seeding

• Seed script for cards, users, and initial balances
• Deterministic — safe to re-run in dev

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Pricing Model

Card price is derived from total supply using a sigmoid function:

price = P_min + (P_max - P_min) / (1 + e^(-k * (supply - midpoint)))

• P_min / P_max — floor and ceiling price bounds
• k — steepness of the curve (controls how fast price rises)
• midpoint — supply at which price is halfway between min and max

All arithmetic uses decimal.js to prevent precision loss at scale.

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API Reference (V1)

Auth

Method	Endpoint	Description
POST	/api/auth/signup	Register new user
POST	/api/auth/login	Login, returns session
POST	/api/auth/logout	Invalidate session

Cards

Method	Endpoint	Description
GET	/api/cards	List all cards with current prices
GET	/api/cards/:id	Get single card detail

Trade

Method	Endpoint	Description
POST	/api/trade/buy	Buy shares of a card
POST	/api/trade/sell	Sell shares of a card
GET	/api/trade/history	Get user's trade history

Wallet

Method	Endpoint	Description
GET	/api/wallet	Get current balance
GET	/api/wallet/transactions	Get transaction log

Portfolio

Method	Endpoint	Description
GET	/api/portfolio	Get all holdings with current value and P&L

Leaderboard

Method	Endpoint	Description
GET	/api/leaderboard	Get top players ranked by portfolio value

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Getting Started

Prerequisites

• Bun >= 1.0
• Node.js >= 18 (for Next.js)
• A Neon PostgreSQL database
• A Supabase project (Auth + Realtime)
• An Upstash Redis instance

Installation

# Clone the repo
git clone https://github.com/yourusername/tropex.git
cd tropex

# Install dependencies
bun install

Environment Variables

Create .env files in both apps/server and apps/web.

apps/server/.env

DATABASE_URL=
DIRECT_URL=
SUPABASE_URL=
SUPABASE_SERVICE_ROLE_KEY=
UPSTASH_REDIS_REST_URL=
UPSTASH_REDIS_REST_TOKEN=
PORT=3001

apps/web/.env.local

NEXT_PUBLIC_SUPABASE_URL=
NEXT_PUBLIC_SUPABASE_ANON_KEY=
NEXT_PUBLIC_API_URL=http://localhost:3001

Database Setup

# Push schema to your Neon database
cd packages/db
bunx prisma db push

# Seed initial data
bun run seed

Development

# Run both apps concurrently from root
bun run dev

Or individually:

# Backend (runs on :3001)
cd apps/server && bun run dev

# Frontend (runs on :3000)
cd apps/web && bun run dev

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Roadmap

V1 — Core Trading (Backend complete, Frontend in progress)

• Auth system
• Cards API + pricing engine
• Trade, Wallet, Portfolio, Leaderboard APIs
• Database seeding
• Cards display page
• Marketplace page
• Card detail page
• Leaderboard page
• Wallet page
• Profile page

V2 — Creator Economy

• Tiered IPO fee system for card creation
• Creator dashboard
• Revenue sharing mechanics

V3 — AI Newspaper

• Claude API-powered in-game news feed
• Market events generated from trade activity
• AI commentary on price movements

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Contributing

This is a personal project — not open to contributions at this stage.

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