Agencies charge $8,000 for a mini-game. I built one for $20 with Fable 5

Gamification agencies sell custom browser mini-games to brands for thousands of dollars per project. Marketing teams buy them because an interactive thing holds attention far longer than a banner. Until recently building one meant hiring a studio: a developer, a 3D artist, weeks of work.

I built a GTA-style browser game in one chat with Claude Fable 5. Driving, shooting, gang AI, police chases, a radar minimap. No game engine, no assets, no code written by hand. One HTML file that runs anywhere. The skill that produced it is exactly what those agencies are selling, minus the studio.

This is the full breakdown: every prompt I used, the code it produced, how to ship it in one minute and how to price this as a service.

Bookmark this and follow. I build AI systems and automation pipelines and I document what actually works.

What the game has

Third-person driving with arcade physics

First-person mode when you exit the car, with a crosshair and weapon

A cul-de-sac neighborhood: houses, lawns, palms, power lines, parked cars

A gang faction with aggro AI that shoots back

Police that spawn at 2 wanted stars, chase you and ram your car

GTA-style HUD: green dollars, wanted stars, HP bar, radar minimap with enemy dots

A WASTED screen on death

Total cost: a Claude subscription. Total time: one evening of typing messages.

The prompt chain

The biggest mistake people make is asking for everything in one giant prompt. That produces a broken mess. I built this in 6 iterations, one feature layer per message. Here is the chain, cleaned up:

Prompt 1 - the skeleton:

Prompt 2 - on-foot mode:

Prompt 3 - the iconic location:

Prompt 4 - combat:

Prompt 5 - environment polish:

Prompt 6 - the HUD that sells the screenshot:

That last prompt matters more than it looks. Nobody screenshots gameplay logic. They screenshot the minimap and the dollar counter.

Proof it's real code

This is the actual cop AI from the file. Each police car steers toward you with a turn-rate limit, so chases look natural instead of robotic:

And the radar minimap is just a 2D canvas drawn every frame on top of the 3D scene:

I did not write a line of this. I described behavior, Claude wrote the implementation, I tested and reported what felt wrong.

Shipping takes one minute

The game is one HTML file. Three free options:

No backend, no database, no server costs. The only dependency is three.js loaded from a CDN.

The honest math

I'm not going to tell you this exact game prints $10k a month. It won't. Here is what a project like this actually does:

The real product here is not the game. It's the proof that you can go from a sentence to a working interactive product in hours. That's what clients pay for.

Three rules that made it work

One feature layer per message. Skeleton first, then movement, then combat, then polish. Every step stays playable.

Send screenshots back. I pasted reference screenshots of the look I wanted and screenshots of bugs. Claude reads images. "Make it look like this" with a picture beats three paragraphs of description.

Report what feels wrong, not what to rewrite. "I can drive but I can't walk" got a precise fix. Asking to rewrite the controls from scratch would have broken something else.

Most people will read this and save it for later. A few will open Claude tonight and have a playable link to post by tomorrow. The prompt chain is right here. Use it.

I post breakdowns like this one a couple of times a week in my Telegram - prompt chains, AI monetization experiments, what worked and what flopped: t.me/GipArcAI

Prompts

Viral content:
One playable link in a thread outperforms
a video-only post. People share things they
can click. That's followers, and followers
are the asset.
 
Client demos:
"I can build you an interactive product demo
in 2 days" lands very differently when you
show a working game as proof.
Realistic price per custom interactive piece: $300-1,500.
 
Reskins:
The same codebase becomes a branded mini-game
for a business: their product instead of cars,
their mascot instead of NPCs. Agencies quote
$3,000-8,000 for this. As a solo builder you
can undercut them at $500-2,500 and still
deliver in days instead of weeks.
Build once, sell the adaptation many times.
 
Game portals:
itch.io and similar take browser games with
optional donations. Small money, but passive
and it builds a public portfolio.

var want = Math.atan2(dx, dz);
var diff = want - cop.heading;
while (diff > Math.PI) diff -= Math.PI * 2;
while (diff < -Math.PI) diff += Math.PI * 2;
cop.heading += Math.max(-1.8 * dt, Math.min(1.8 * dt, diff));
 
if (distSq > 100) {
  // chase until close, then stop and shoot
  cop.x += Math.sin(cop.heading) * 13 * dt;
  cop.z += Math.cos(cop.heading) * 13 * dt;
}

Redesign the map as a cul-de-sac: a ring road around
a dirt circle, houses facing the ring, a two-story house
at the top, one entry street from the south.
Add police: at 2 wanted stars black-and-white cop cars
with flashing lights spawn, chase me and shoot.
I can disable them with 3 hits for bonus cash.

Netlify Drop:    drag the file onto netlify.com/drop, get a link
GitHub Pages:    push to a repo, enable Pages in settings
Vercel:          vercel.com, import, deploy

Add shooting on F or Space, works on foot and as a drive-by
from the car. Add a rival gang in purple that walks its own
territory. If I hit one, nearby gang members aggro and
shoot back. Give me an HP bar and a WASTED death screen
with respawn.

function dot(x, z, color, r) {
  var p = worldToMap(x, z);
  ctx.fillStyle = color;
  ctx.beginPath();
  ctx.arc(p[0], p[1], r || 2.4, 0, 6.29);
  ctx.fill();
}
gang.forEach(g => dot(g.x, g.z, '#c46af0'));  // purple
cops.forEach(c => dot(c.x, c.z, '#5a9af0'));  // blue

Make it look like San Andreas, not Minecraft: hazy sky,
stucco houses with pitched roofs and porches, three types
of vegetation (palms, round trees, bushes), street lamps,
power poles, parked cars, a distant downtown skyline
silhouette in the fog. Translate all UI to English.

Build a GTA-style open world mini game as a single HTML file
using three.js from CDN.
 
Requirements:
- procedural low-poly city: roads, buildings, sidewalks
- drivable car with WASD/arrow controls, third person camera
- wandering pedestrian NPCs
- wanted stars that rise when you cause chaos and decay over time
- HUD with speed and score
- touch buttons so it works on mobile
 
Keep everything in one file. No build step, no npm.

First person camera when on foot, with head bob and
a crosshair. GTA-style HUD: green money counter,
five-star wanted row, weapon name, and a circular radar
minimap in the corner showing roads, gang members as
purple dots, cops as blue dots and my car in green.

Add the ability to exit the car with E and walk around
on the same controls. Add a button for mobile.
Show the current mode in the HUD.

Links

• t.me/GipArcAI