how to build

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Build real things with an agent at your side.

This site teaches you to make games, apps and websites with Claude Code and Codex. These are agents: programs that read your files, write code and run commands while you tell them what you want. You start with nothing installed and end with things online that your friends can open on their phones.

Do the 10-minute first win Go to chapter 1

Who this is for

You have never opened a terminal, or you opened one and closed it fast. You might be a teenager with a game idea. You might be someone who likes tech and wants to see what these agents can really do.

You don't need to know how to code. You need a computer (Mac, Windows or Linux), some patience, and a few evenings.

The honest deal

Some of this costs money. Here is all of it, up front.

Prices change. Check claude.com/pricing and chatgpt.com/pricing before you pay.

The 10-minute first win

Before you install anything, make a web page. You only need a browser and a laptop or desktop. The free plan of Claude or ChatGPT is fine for this part.

  1. Open claude.ai or chatgpt.com and sign in.

  2. Paste this in. Change the name to yours.

    Make me a web page in a single HTML file. It shows the name Sam in big letters in the middle of the screen. Under the name is a button that says "Surprise me". Each click changes the background to a random color and shows a random fact about space. Put the CSS and JavaScript inside the same file. Reply with only the code, in one block.

    You should see: a block of code that starts with <!doctype html> or <html>. Copy all of it. There is usually a Copy button on the block.

  3. Save the code as a file called index.html.

    Mac

    Open TextEdit. In the menu, pick Format, then Make Plain Text. Paste the code. Save it to your Desktop as index.html. If it asks, choose "Use .html".

    Windows

    Open Notepad. Paste the code. Choose File, then Save As. Set "Save as type" to "All files". Name it index.html and save it to your Desktop.

    Linux

    Open your text editor (gedit, Kate or Text Editor). Paste the code. Save it to your Desktop as index.html.

  4. Double-click index.html on your Desktop.

    You should see: your name, big, in your browser. Click the button. The color changes and a space fact appears.

That's the whole idea of this site, in small. You said what you wanted, the agent wrote it, and you checked it. The rest of the guide does the same thing with bigger projects, and the agent works on your files directly, so there's no copy and paste.

What you'll be able to build

The projects go from one star (an evening) to three stars (a real project you work on for a while).

See all nine projects →

The path

Eight chapters. Do them in order. Each one ends with something working.

  1. Set up your computer

    Open a terminal and install git and Node.

  2. Get Claude Code

    Install it, log in with your plan, and run your first session.

  3. Get Codex

    The same, for Codex, if you use ChatGPT.

  4. How to work with an agent

    Write a brief, ask for a plan, build, check, and undo when it goes wrong.

  5. Save it on GitHub

    Keep every version of your work, safe and off your laptop.

  6. Put it online with Cloudflare Pages

    Get a web address anyone can open.

  7. Keep data

    Save scores, posts and photos, from the browser up to a real database.

  8. Going further

    Subagents, skills, hooks, reviews, costs and staying safe.

What this is not

This is not a course that makes you a programmer in a weekend. The agent writes most of the code. You will read a lot of it, ask about the parts that look strange, and slowly start to understand it. That understanding is what lets you build bigger things.

It is also not magic. The agent gets things wrong. A big part of this guide is how to notice that and how to get back to a version that worked.