OpenAI's $200 Codex Chromatic turns prompts into Game Boy games

Felix Laurent 9 Nov 2026 5 min read

Big tech

OpenAI now sells a Codex edition of the ModRetro Chromatic, a Game Boy Color-style handheld, for $200 on its Supply Co store. The OpenAI Developers account announced it on X on November 9, 2026. Buyers get a rewritable cartridge and a code that lets Codex write their own games onto it.

The device first appeared at DevDay in September, when about 2,500 attendees got one as a gift. Resale prices then climbed past $1,000. Now anyone in the supported regions can buy one, while stock lasts.

What the Codex Chromatic includes

The Chromatic is ModRetro's FPGA handheld, which runs original Game Boy and Game Boy Color cartridges on hardware instead of emulation. The Codex edition has a transparent shell, a 2.56-inch backlit screen at 160 by 144 pixels and Gorilla Glass. It also has a headphone jack.

The box adds two things the regular model lacks:

A Codex Cartridge: a rewritable cartridge for games you build
An activation code: it unlocks Chromatic Developer Mode on your computer, which lets you write ROMs to that cartridge

According to coverage by NewMobileLife, extra Codex Cartridges cost $50 each. A Codex-branded hard case with room for one more cartridge is also listed. ModRetro, not OpenAI, handles warranty and support.

Here is the 45-second promo OpenAI posted with the launch:

Ever thought about building your own games? The Codex edition @modretro Chromatic is now on Supply Co.

With the ModRetro Chromatic plugin in Codex, you can design levels, animate sprites, and playtest on your handheld.

Speedrun checkout while Codex builds your ROM 😉
— OpenAI Developers (@OpenAIDevs) November 9, 2026

The store ships to the US, Canada, Australia, New Zealand, Japan, the UK and the EU. Sales are final. Resell Calendar reported that units were still available more than 40 minutes after launch. The page later switched to a restock notice, with new stock expected around November 19.

The hardware is only half the product. The other half lives inside Codex.

How the ModRetro plugin in Codex works

The ModRetro Chromatic plugin installs from the Plugins section of the Codex desktop app. Once added, a user mentions it in a project chat and asks Codex to set up the build tools.

Under the hood, the plugin works with three standard homebrew toolchains:

GB Studio: visual projects with custom logic, which stay editable after Codex works on them
GBDK-2020: games written in C
RGBDS: games written in assembly

Codex can draw sprite sheets, edit backgrounds and collision maps, and run the game in an emulator inside its built-in browser. An "Annotate game" mode lets you freeze a frame, select a sprite and describe a change. Codex can also playtest on its own by sending button presses and checking the frames that come back.

With a USB cable, gameplay streams live to the handheld. When the game is ready, "Install on Chromatic" writes the ROM to the cartridge after a firmware update and the activation code. OpenAI's guide warns that this erases the cartridge's previous game and can wipe its saves.

Building and playing in the emulator works without the device. Writing to a cartridge needs the code from a DevDay or Codex edition unit. ModRetro's terms limit the mode to original games, with no piracy or copy protection workarounds.

OpenAI's showcase page lists 13 games built this way, from FlapGPT and Pizza Dash to Hollow Descent. All of them can be played in a browser or downloaded as ROMs. The project started at DevDay, which explains why the device was already in demand.

From DevDay gift to Supply Co product

OpenAI handed the Chromatic out at DevDay on September 29, the event where it launched GPT-6.1 Sol and Dots. Attendees received a transparent DevDay edition with a blank cartridge and an activation code. Resell Calendar tracked an open-box unit selling for $999.99 the next morning and $1,300 two days later.

The store launch followed a teaser on November 8 that showed an OpenAI box with the handheld on the lid. The same pattern played out in July with the Codex Micro, a $230 macropad made with Work Louder. It sold out in about 12 hours and later appeared on eBay for up to $1,250.

Supply Co itself began as an internal employee shop. It opened to the public in July 2026 with socks, T-shirts and sweaters. The Codex hardware drops turn it into a marketing channel for the coding agent.

The partner choice brings its own baggage.

ModRetro and the Palmer Luckey connection

ModRetro is the hardware company of Palmer Luckey, who founded Oculus and later the defense firm Anduril. It announced the Chromatic in June 2024 for $199, with a magnesium alloy shell and Tetris bundled with preorders. Later versions added a cheaper plastic model and an N64-style console called the M64.

The Anduril tie has drawn pushback. In December 2025, ModRetro released an Anduril edition coated in the material used on Anduril's Ghost drone. Retro gaming site Time Extension then announced it would stop covering ModRetro products. When the OpenAI partnership was first shown, Retro Dodo raised copyright concerns and called some of the showcase games "slop."

The reaction to Monday's launch was mixed as well.

How developers reacted

The post passed 280,000 views and 250 replies within a day. Owners from DevDay shared their own builds. One attendee posted a Balatro-style card game running on the handheld. Another buyer was waiting on cartridge stock and planned to check back on November 19.

Many replies criticized the priorities instead. Several users said they wanted stronger models from OpenAI, not a handheld. One called it "cheap emulator hardware with a custom SDK" and objected to paying $50 for a blank cartridge. Others questioned international shipping costs, with one quoting €76.

Those complaints point to who the product is really for.

Is the Codex Chromatic worth $200

For people who always wanted to make a Game Boy game, the bundle removes most of the friction. Codex handles the toolchain, the sprites and the playtesting, and the result runs on real hardware from a real cartridge. The games also stay standard GB Studio or C projects that can be edited without Codex.

The cost is the catch. Building in the emulator is free with a Codex plan, and only the cartridge step needs the bundle. At $200 plus $50 per extra cartridge, the price buys a physical toy and the license to flash it. For Codex fans and collectors, it is a fun object that DevDay made scarce. For anyone curious about AI-made retro games, the plugin and emulator are the better place to start.