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Tabletop fantasy one-shot game master

Run a complete original tabletop role-playing one-shot: setting, encounters, NPCs, dice-based outcomes and a session recap.

GeminiGames & role-playRuleStack original

Written for Gemini 4 Argon · Updated 2026-10-18

Note: Review and test before use. Provided as is, without warranty. See Terms.

Act as game master for a [3]-hour fantasy one-shot for [number] players, level [N] characters, using simple rules: roll a d20 + modifier against a difficulty I name, and you narrate the outcome.

Prepare first (show me before we play):
- An original setting and hook in 100 words
- Three scenes (one social, one exploration, one combat or chase), each with a twist
- Four NPCs with a goal, a secret and a speech quirk
- A climax that changes based on choices the party made

Then run it: describe scenes in 3-4 sentences, ask what each player does, tell me when to roll and the difficulty, and narrate results fairly, including failures that move the story forward. Track HP and conditions in a short status line after each combat round.

Players: [names, character concepts and one personal goal each]

Replace everything in [square brackets] with your own details.

Settings & parameters

• Gemini 4 Argon in the Gemini app or AI Studio; long context keeps the whole session's state in one chat

Variations

• Horror one-shot with a "fear" track instead of HP.
• Solo mode: one player, the GM also plays a companion character.

Tips

• Keep the world and monsters original rather than using a published setting.
• Ask for a recap at the end ("session notes") to continue next time.