Dark fantasy roleplay with an AI that does not flinch

Dark fantasy needs magic that costs something and characters who make bad choices for good reasons. Filtered models keep turning it back into a quest with a happy ending.

What dark fantasy needs

Dark fantasy mixes the furniture of fantasy, swords and sorcery and old kingdoms, with horror and tragedy. Magic should be dangerous, gods should be unreliable, and the player should be able to do terrible things and have the world respond. The model has to write morally grey characters with real conviction, depict violence and cruelty when the plot demands it, and keep a mood of decay without every scene being a massacre.

How filtered models sand it down

The common failures are moralizing and softening. A mainstream model will let your necromancer raise the dead and then have an NPC deliver a speech about how wrong it was. Torture scenes cut away. A villain's cruelty gets described as "unspeakable" instead of shown. Some models refuse any scene where a sympathetic character does something unforgivable, which is half the genre.

With an abliterated model those refusals go, and what is left is a tone problem you can steer with the prompt.

Card and lorebook advice

• Give magic a price list. "Blood magic costs memories. Healing transfers the wound to someone nearby." The model will apply concrete costs consistently; vague "dark magic" turns into fireworks.
• Write NPC motives in one line each. A priest who sells absolution because the temple is starving is more useful than a page of backstory.
• Use a lorebook for factions. Dark fantasy plots are political, and keyword-triggered entries keep the model from inventing a new church every session.
• Say that victory is allowed but rarely clean. Otherwise the model will either never let you win or make every win free.

Sample system prompt

You are the narrator of a dark fantasy story in a dying kingdom.
Magic always has a cost, applied consistently. Gods are distant and unreliable.
NPCs act on their own motives and do not lecture {{user}} about morality.
Violence and cruelty are depicted with weight and consequence, not glamour.
Mood: decay, cold, old stone, poverty under ornament. Keep replies under 300 words.
Never write {{user}}'s actions or dialogue.

Samplers and model choice

• Temperature 0.9. Fantasy benefits from invention: names, rituals, strange places.
• Min-p 0.05 to 0.07.
• Repetition penalty 1.05 to stop "ancient" and "shadows" turning up every paragraph.

Use outlaw-1 to start. A campaign with a big lorebook eats tokens, and its pricing ($0.30 in, $1.00 out per million) is the lowest on the model line. For political plots with many factions, switch to glm-5.3-outlaw for the sessions where scheming matters.

Failure modes and fixes

• NPCs moralize. Add "NPCs may disapprove but act on it rather than lecturing".
• Everything is grim all the time. Ask for small moments of warmth. Darkness reads stronger against contrast.
• Magic has no rules. Put the cost table in an always-on lorebook entry.
• The model writes your character's reactions. Shorten replies and repeat the rule at the end of the system prompt, where it carries more weight.

FAQ

Related

Grimdark roleplay: an AI narrator for a world with no clean handsGrimdark is a test of whether a model will let the story be ugly without apologizing for it. Most mainstream models fail inside the first battle.

High fantasy roleplay: worldbuilding, battles and long campaignsHigh fantasy is less about darkness and more about scale: maps, histories, a party with distinct voices and battles that matter. The hard part is consistency over hundreds of turns.

Dungeon crawls and text adventures with an AI game masterA text adventure is a game first. The narrator has to say no, keep a map, and let you die, which is everything an assistant model is tuned against.