# Chromatic: DevDay Edition Quickstart Guide > Welcome to the QuickStart Guide for the ModRetro Chromatic Codex Edition Following these steps will allow you to dream up your own Chromatic game First le Source: https://support.modretro.com/en_us/chromatic-devday-edition-quickstart-guid-By1iOlcMg Last updated: 2026-09-29T15:59:59.626Z Welcome to the Quick-Start Guide for the ModRetro Chromatic: DevDay Edition. Following these steps will allow you to dream up your own Chromatic game. First, let’s set you up with Codex and the ModRetro Chromatic Plugin. ## Setup & Installation ### Update Your Chromatic Download the [Chromatic Firmware Updater](https://support.modretro.com/en_us/articles/chromatic-firmware-updater-ryhoYnzCx) and follow the instructions on the linked page to update your Chromatic. ### Activate Chromatic Developer-Mode for Your Computer Included with your ModRetro Chromatic: DevDay Edition is an activation code to enable Chromatic Developer-Mode on your computer. This developer-mode allows you to write the games you make to the cartridge included with your ModRetro Chromatic: DevDay Edition. In Chromatic Firmware Updater, press `Ctrl-I` (`Cmd-I` on macOS) to open a dialog to enter your activation code. ![Entering an activation code in the Chromatic Firmware Updater](https://cdn.kustomerhostedcontent.com/media/67995ea3b9bd549006863fa7/6bcdf4995cdb7679f645b79ad2359e4b.png) Once activated, Codex will be able to flash games onto your physical Chromatic cartridge. ### Install the Codex Desktop App Download and install Codex from [https://chatgpt.com/codex/](https://chatgpt.com/codex/). ### Install the ModRetro Chromatic Plugin In Codex, open up the Plugins tab on the left side of the screen and search for “ModRetro Chromatic.” ![Searching for the ModRetro Chromatic Plugin in the Codex Plugins tab](https://cdn.kustomerhostedcontent.com/media/67995ea3b9bd549006863fa7/05c038591ac1885fcd74634852637738.png) Press Install. After, you may ask Codex: Prompt Set up @ModRetro Chromatic Plugin so I can create games, build ROMs, and run automated playtests. Check what’s already installed and prepare the missing dependencies. ## Making Games with Codex In a new chat press “@” and search for “ModRetro Chromatic Plugin.” Press enter to add the plugin to the current prompt. Describe the game you would like to make and the plugin will provide the required skills to create this game for Game Boy Color compatible devices and emulators. ![A Codex prompt with the ModRetro Chromatic Plugin added](https://cdn.kustomerhostedcontent.com/media/67995ea3b9bd549006863fa7/6000d5d839f92b5c890c423550daeda6.png) Need an idea? Try one of the following example prompts: #### Create a new game Prompt Create and select a new GB Studio project at /absolute/existing-parent/MoonGarden. Make a small exploration game where a gardener collects three seeds and plants them to unlock a gate. #### Remix an example game The plugin includes an example game “Wrecklight” that can be remixed into your own game. Prompt Create and select a Wrecklight remix at /absolute/existing-parent/MyWrecklight. Show me its rooms and controls, then help me turn the opening area into an abandoned research station. ## Playtesting Your Game in Emulator Use the built-in emulator to test your game as Codex makes changes. ![A game running in the Codex browser preview emulator](https://cdn.kustomerhostedcontent.com/media/67995ea3b9bd549006863fa7/7fbee597ffa6f7c78eb0f7fa21094eca.png) Prompt Build my selected game and open it in the playable browser preview. Reuse that preview as we make changes. ## Adding Features and Debugging Issues #### Add a scene Prompt Add a village scene to my selected project with three houses, a central fountain, and a character I can talk to. Connect it to the starting area. #### Create new characters and artwork Prompt Create a small robot player sprite with idle and walking animations that fit this project’s style and Game Boy hardware limits. Add it to the game and show it in a scene. #### Update the color palette Prompt Give this scene a moonlit palette with cool blue shadows and warm window lights. Check readability and show the result in the game preview. #### Validate artwork against hardware constraints Prompt Audit my project’s backgrounds and sprites for Game Boy hardware limits. Identify problems and fix any assets that would prevent a successful build. ## Playtesting Your Game on Chromatic Your game can be streamed to your Chromatic to test out how it plays and feels on real hardware. #### Stream live gameplay to your Chromatic Your game will be run in an emulator and streamed to your Chromatic. Prompt Stream a two-minute live demo of my built ROM to the connected Chromatic so I can try its controls, video, and audio. ## Creating a Physical Cartridge When you’ve found a good build, you can flash your game to a real cartridge. Prompt Flash my built homebrew ROM to the connected Chromatic cartridge, then guide me through manual boot, gameplay, and audio checks. ## Explore Games Made by Others See games made by others and share your own at: [https://modretro.openai.chatgpt.site/](https://modretro.openai.chatgpt.site/) **DISCLAIMER:** The Chromatic skill is for original, user-created ROMs only. Don't use it for piracy, emulating commercial games, or getting around protections. Developer mode is at your own risk. You're responsible for anything you create, including making sure you have the rights to any third-party IP. ModRetro doesn't review or endorse user content and isn't liable for claims arising from it. You agree to indemnify ModRetro against those claims. The skill and all user content are provided "as is," without warranties. Use is subject to our [End User License Agreement.](https://modretro.com/eula)