> For the complete documentation index, see [llms.txt](https://docs.fullscreen.no/info/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fullscreen.no/info/game-creator-2-assets/mailbox/guides-and-demo-scene/running-instructions-on-open-letter.md).

# Running Instructions On Open Letter

When a letter is opened for the first time, you can trigger **custom instructions** to enhance gameplay and storytelling.

This is a **powerful tool** for dynamic world-building, use it to:

* Start a quest when the player reads a letter (e.g., “Find and locate Mr. Whiskers” 🐱)
* Unlock new areas, trigger events, or update NPC dialogue
* Reveal hidden lore through interactive letters

Since these instructions **only run the first time the letter is opened**, they ensure meaningful, one-time interactions that feel immersive and intentional.

<figure><img src="https://756218607-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fv2D32cRkVCHsF9VcmKPA%2Fuploads%2FXBX5uYEARKQM3O1KEJuy%2Fimage.png?alt=media&amp;token=3dd66eb2-d39c-4147-a19e-8d9a0a71e115" alt=""><figcaption></figcaption></figure>