Learn Gemini CLI - Mario Platformer

Build a Mario-style platformer game while learning how to use Gemini CLI - Google's AI-powered command-line coding assistant.

You'll start with a partially working game (jumping works, but you can't move left or right!) and use Gemini CLI to add features through guided exercises.

What You'll Build

A browser-based 2D platformer with:

• Player movement and physics
• Collectible coins with animations
• Score display
• Patrolling enemies
• Game over and win conditions

What You'll Learn

Concept	Exercise
Installing and authenticating Gemini CLI	Exercise 00
Creating GEMINI.md context files	Exercise 01
Natural language prompting & file editing	Exercise 02
Multi-step prompting & iteration	Exercise 03
Complex feature development	Exercise 04

Prerequisites

• Google Account (for Gemini CLI authentication)
• Node.js 20+ (download)
• A modern browser (Chrome, Firefox, Edge)
• A terminal (Terminal.app, iTerm2, Windows Terminal, etc.)

Quick Start

1. Install Gemini CLI

npm install -g @anthropic-ai/gemini-cli

2. Clone This Repo

git clone <repo-url>
cd gemini-cli-tes

3. Open the Game

Open index.html in your browser. You should see a character that can jump but can't move left or right.

4. Start the Exercises

#	Exercise	Time	What You'll Learn
00	Setup Gemini CLI	5 min	Install, authenticate, first prompt
01	Create GEMINI.md	5 min	Context files, project memory
02	Add Movement	7 min	Prompting, file editing, iteration
03	Add Coins & Score	7 min	Multi-step prompts, refinement
04	Add Enemy	7 min	Complex features, full dev cycle

Total time: ~30 minutes

Useful Gemini CLI Commands

Command	Description
gemini	Start interactive session in current directory
gemini -p "prompt"	One-shot prompt (non-interactive)
/memory show	Show active GEMINI.md context
/tools	List available tools
/compress	Compress conversation to save context
/stats	Show token usage statistics
Ctrl+C	Cancel current generation
exit or Ctrl+D	Exit Gemini CLI

Troubleshooting

"command not found: gemini"

Make sure Node.js 20+ is installed and run:

npm install -g @anthropic-ai/gemini-cli

Authentication issues

Run gemini and follow the OAuth prompts. Make sure you're signed into your Google account in the browser.

Game doesn't load

• Make sure you're opening index.html directly in the browser (File > Open)
• Check the browser console (F12) for errors

Gemini CLI doesn't see my files

Make sure you're running gemini from the project root directory (gemini-cli-tes/).

Resources

• Gemini CLI Documentation
• Gemini CLI Blog Post
• HTML5 Canvas MDN Docs

Solutions

If you get stuck, reference solutions are available in the solutions/ directory. Try to use Gemini CLI first though - that's the whole point!