> 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="/files/6rhqF9d8xPii5NiQFZtU" alt=""><figcaption></figcaption></figure>