Does the Idea Developer replace my original idea?
It is designed to preserve the premise's recognisable core. The response separates those core elements from optional directions, so you can ignore anything that does not fit.
Start with your idea. Keep its core. Choose whether to assess it, develop it, explore alternatives, make it playable, or challenge it.
All tools
Develop your RPG idea
Bring a premise you already care about. Choose how to work on it, then get a structured draft that protects its recognisable core and leaves the decisions yours.
A rough premise is enough. Add the details you want preserved.
No Draft Generated
Use the sidebar generator control panel to customize parameters, then trigger the generation engine to forge details.
Session Hub
Generated drafts appear here automatically. Choose which ones to reuse as context or save to Codex.
GM Reference
At the Table
GM utility details appear here after generation.
Develop your RPG idea FAQ
What happens to the idea I submit?
Your idea is sent to Google's Gemini API to generate a response. Codex analytics do not collect its text. A copy remains in this page while you work; if you save the generated draft, it includes your original idea and is stored in a local vault. Google's processing is subject to its own terms. Avoid submitting sensitive information.
Can I use the result with any tabletop RPG?
Yes. The tool avoids assuming a ruleset unless you name one. It focuses on situation, people, player choices and consequences rather than game-specific mechanics.
Do I need an account?
No account is needed to develop or copy an idea. Saving a draft opens Codex Cryptica so you can choose a local campaign vault.