> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gx402.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Hello World with Gx402

> Your first Gx402-powered game

<Card title="🚧 Coming Soon" icon="construction" color="yellow">
  This tutorial is part of the **early developer preview** for Gx402.\
  The SDK and its purchase functionality are still in active development — expect updates, new APIs, and improved stability soon.
</Card>

# Hello World with Gx402

In this quick tutorial, you'll create your **first application using the Gx402 SDK**.\
We’ll build a simple “game” that demonstrates the core idea behind **x402-powered in-game purchases**.

***

## What You'll Build

A small web page with a single button that lets players **buy a Legendary Sword** using **Gx402 payment functionality**.\
This example focuses on the **core purchase flow**, keeping things as minimal as possible.

***

## Prerequisites

Before you start, make sure you have:

* 🧠 Basic knowledge of **JavaScript** and **HTML**
* 💻 **Node.js** and **npm** installed
* 🔑 (Optional) Your **Gx402 API key** from the [Gx402 Dashboard](https://Gx402.com)

***

## Step 1: Set Up Your Project

Let’s start fresh.

```bash theme={null}
mkdir Gx402-purchase-example
cd Gx402-purchase-example
npm init -y
npm install @Gx402/sdk
```