Building a Game with Free AI Tools: ChatGPT + Gemini Case Study

Mar 24, 2026

The Cost Barrier

I wanted to build a game, but I kept reading that I needed premium AI tools. Claude Pro at $20/month. Cursor Pro at $20/month. That’s $40/month before writing a single line of code.

Then I found a post on r/AskVibecoders that changed my thinking. A developer shipped a complete Brick Breaker game to the App Store using only ChatGPT Free and Gemini Free. Total cost: $0.

The time breakdown surprised me: 2 days to build the core game, 5 days to optimize performance. That ratio tells you something important about AI-assisted development.

What “Vibe Coding” Actually Means

Vibe coding is writing software by describing what you want in natural language and letting AI generate the code. You guide the architecture, test the output, and iterate. The AI handles the syntax and implementation details.

This works particularly well for games because:

Game logic is visual and easy to describe
You can test immediately by playing
Bugs are obvious (the game doesn’t work right)
Performance issues show up in frame rate

The key insight from the Reddit post: AI accelerates building, but optimization still takes human judgment and time.

The Free AI Game Development Stack

I mapped out what tools you actually need:

Planning & Architecture:
├── ChatGPT Free (general reasoning, design decisions)
└── Gemini Free (alternative perspective, code review)

Code Generation:
├── ChatGPT Free (primary coding)
├── Gemini Free (secondary/validation)
└── Character limits: work in small chunks

Game Engine Options:
├── Godot (free, open-source)
├── Phaser.js (web games)
├── Unity Personal (free tier)
└── Choose based on target platform

Asset Creation:
├── Midjourney (images - has free tier limits)
├── DALL-E (through ChatGPT Plus, but Bing Image Creator is free)
└── Canva (UI elements, free tier)

The critical constraint with free tiers is character limits. You can’t ask for an entire game at once. You need to break it into components.

How I Approach This

Based on the Brick Breaker case study, here’s the workflow that works:

Days 1-2: Core Building

┌─────────────────┐     ┌─────────────────┐
│  Describe One   │────▶│  ChatGPT        │
│  Component      │     │  Generates Code │
└─────────────────┘     └────────┬────────┘
                                 │
                                 ▼
                        ┌─────────────────┐
                        │  Test in Engine │
                        │  Play Immediately│
                        └────────┬────────┘
                                 │
                                 ▼
                        ┌─────────────────┐
                        │  Gemini Review   │
                        │  Cross-check     │
                        └─────────────────┘

I start with small, focused prompts. For a paddle in a breakout game:

I'm building a simple brick breaker game in Phaser.js.
Help me create the paddle movement logic:
- Paddle should follow mouse/touch
- Paddle stays at bottom of screen
- Smooth movement with bounds checking

Please provide just this one component, fully commented.

This prompt gives ChatGPT a clear, bounded task. Here’s what it might generate:

class Paddle {
  constructor(scene) {
    this.scene = scene;
    this.sprite = scene.physics.add.sprite(
      400, 550, 'paddle'
    );
    this.sprite.setImmovable(true);
    this.sprite.body.allowGravity = false;
  }

  update(pointer) {
    // Smooth movement following pointer
    this.sprite.x = Phaser.Math.Clamp(
      pointer.x,
      this.sprite.width / 2,
      this.scene.cameras.main.width - this.sprite.width / 2
    );
  }
}

Then I copy this into my game project, test it, and move to the next component.

Days 3-7: Optimization

The Reddit post reveals the real time sink: 70% of time went to optimization. AI-generated code works, but it’s not always efficient.

I check these specific performance issues:

## Performance Issues to Check:
- [ ] Object pooling implemented?
- [ ] Collision detection efficient?
- [ ] Sprite sheets optimized?
- [ ] Audio files compressed?
- [ ] Update loop doing unnecessary work?
- [ ] Memory leaks in event listeners?
- [ ] Mobile performance acceptable?

For each issue, I ask the AI specifically. “How do I implement object pooling for bullets in Phaser.js?” is a focused optimization question.

What Not to Do

I made these mistakes when I first tried vibe coding:

Asking for too much at once:

Write me a complete brick breaker game with:
- Multiple levels
- Power-ups
- High score system
- Mobile touch controls
- Particle effects

This hits character limits and produces low-quality code. The AI can’t reason effectively about all these systems at once.

Not testing incrementally:

I once generated three components before testing any. When something broke, I couldn’t tell which component caused it. Now I test after every single component.

Ignoring game engine documentation:

AI sometimes suggests outdated APIs. Phaser 2 syntax in a Phaser 3 project. I keep the official docs open and cross-reference.

Skipping optimization:

The first version runs at 60fps on my laptop. Then I test on mobile and it drops to 15fps. The 2-day build / 5-day optimize ratio from the Reddit post is real.

Why Free Tiers Work

The free tiers of ChatGPT and Gemini have limits, but they’re sufficient for game development:

Limitation	Workaround
Character output limits	Break tasks into small chunks
Rate limits	Use ChatGPT and Gemini alternately
No codebase context	Paste relevant snippets when needed
No file operations	Copy-paste manually

The workaround for character limits is actually beneficial. It forces you to think in components rather than monoliths. Your code ends up more modular.

When to Consider Paid Tools

Free works for learning and shipping your first games. But I’ve found scenarios where paid tools help:

Large codebase context (Cursor Pro knows your whole project)
Faster iteration (no rate limits)
More powerful models (Claude Sonnet 3.5 vs free tier limits)
Team collaboration features

Start free. If you’re spending more time copy-pasting than building, then consider upgrading.

A Practical Test

I tried this approach with a simple game idea. Here’s what happened:

Day 1: Generated player movement and basic collision. Both worked first try.

Day 2: Added enemies and scoring. Had to iterate twice on collision logic.

Day 3: Tested on mobile. Frame rate dropped to 20fps.

Day 4-5: Optimized with ChatGPT help. Object pooling, sprite batching, reduced draw calls.

Day 6: Mobile performance hit 55fps. Good enough to ship.

Day 7: Final polish, bug fixes, deployed.

Total cost: $0. Total time: one week of evenings.

The 70/30 Insight

The Brick Breaker developer spent 30% of time building and 70% optimizing. This ratio holds across AI-assisted projects I’ve seen.

AI generates working code quickly. But “working” and “optimized” are different. The human still needs to:

Profile and identify bottlenecks
Ask the right optimization questions
Test on target devices
Make architectural decisions

This is why premium AI tools don’t eliminate development time. They accelerate the easy part. The hard part—performance, user experience, polish—still requires human judgment.

What I’d Do Differently

Looking back at the Brick Breaker case study, I’d adjust my approach:

Start optimization earlier - Don’t wait until the whole game is built
Test on target devices sooner - Mobile reveals issues desktops hide
Use both ChatGPT and Gemini - Cross-checking catches issues
Keep prompts focused - One component per prompt, always
Document as I go - AI doesn’t always add good comments

Summary

You can build a complete, shippable game using only free AI tools. The Brick Breaker developer proved it. ChatGPT Free and Gemini Free handled everything from game logic to optimization suggestions.

The key constraints are character limits (work in small chunks) and the 70/30 time split (build fast, optimize slow). Free tiers work because game development naturally breaks into components. Each component fits within AI output limits.

Start with free tools. Ship something. Then decide if you need premium features. The zero-cost path works.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!