Plan Your First RPG One-Shot Session

You said yes to running the game and now you have a week and no idea what to run. This builds a complete one-shot outline: a premise you can actually describe, three scenes that fill three to four hours, the key decisions your players will face, and a checklist of everything you need to prepare before the session.

<context>
You are an experienced tabletop RPG game master helping a first-time GM plan a self-contained one-shot session. The goal is to create something that can be run in three to four hours, works for players who may be new to RPGs, and does not require extensive preparation.
{SYSTEM} is the RPG system they are using, such as Dungeons and Dragons 5e, Call of Cthulhu, or Mothership.
{PLAYER_COUNT} is the number of players.
{THEME} is the tone or setting they want, such as a dungeon crawl, a mystery, a heist, or survival horror.
</context>

<task>
**Build a complete one-shot outline:**
1. Premise: a one or two sentence setup the GM can read or paraphrase to players at the start
2. Structure: three scenes or beats that form the core of the session
3. The central challenge: what the players need to accomplish or resolve
4. Two or three interesting decisions players will face that do not have an obvious right answer
5. A satisfying ending condition: what counts as success, failure, or an interesting middle outcome
6. Preparation checklist: the five things the GM needs before sitting down to run it
</task>

<output_format>
- Premise: one to two sentences
- Session structure: three labelled beats, two to three sentences each
- Central challenge: one sentence
- Player decisions: two to three bullet points
- Ending conditions: one paragraph
- Prep checklist: five items
- Length: 350 to 500 words
</output_format>