The dice are real.

First, the brain.

On July 1 every live endpoint moved from Sonnet 4.6 to Sonnet 5: Wargamer, the Kriegsspiel umpire, Kriegsspiel rules Q&A, the Kriegsspiel AI player, the Matrix referee, and Chat. The new RPG mode launched on Sonnet 5 directly.

The flip was not a one-line model swap, and the reason is worth spelling out. Sonnet 5 ships with adaptive thinking on by default, and that hidden thinking draws from the same token budget as the visible answer. On a strict-format umpire with a tight output cap, the thinking can silently eat the whole budget and the answer comes back empty. Before touching production we replicated each endpoint’s exact live request against the new model, watched two of the six break every complex turn, and then shipped the migration as one bundled change: new model, thinking explicitly disabled, output caps hardened, each endpoint re-validated with a contract harness before and after deploy.

What you should notice as a user is close to nothing. Same section formats, same speed; Chat’s time to first token held under two seconds in validation. The model underneath is stronger at the actual work, and everything you already subscribed to upgraded in place.

The new table.

RPG GM mode is live at hammerstein.ai/rpg, included with every subscription. The rest of this site is daylight staff college, cream paper and navy ink. This room is the table at night: dark ground, narration set in the site’s serif, and mechanical truth kept apart in mono, in its own log. In there you are not reading a framework. You are playing a character while a neutral referee runs the world.

The GM’s stance comes from the same discipline that runs the wargame umpires. It narrates lean and sensory. It never decides what your character feels or believes. Failure always costs something: a failed check carries a complication or ticks a clock, never a flat nothing-happens. Death is allowed when the mechanics and the fiction support it. The verification gates that keep the wargamer surfaces from yes-anding a bad plan are the same gates that keep this GM from handing you a win because you typed confidently.

The dice are real.

Ask a plain LLM to GM a game and it “rolls” by generating a plausible number. Nothing stops it drifting toward the numbers that keep you comfortable, and nothing lets you catch it when it does. This table removes the choice.

When you start a campaign, the server fixes a random seed and stores it with the campaign. Every die that campaign will ever roll is drawn from a numbered tape derived from that seed by a fixed function (FNV-1a into SplitMix64, over the seed, the tape position, and the die type). Position 14 of your campaign is the same d20 whether it gets rolled tonight or never. The model is handed the next stretch of tape each turn, must consume entries in order, and must echo every die it uses in the mechanical log, in the open, as ROLL d20=16.

Then the table checks the echo. The server parses every roll the GM claims and compares it against the tape. A mismatched die gets one correction pass; if the retry still does not match, the turn is rejected outright rather than shipped with an invented roll. And each turn’s response carries the seed, the tape position before and after, and the exact values consumed, so the campaign’s dice history is inspectable end to end.

The GM never rolls. It is handed dice drawn before the session started, ordered to show each one it uses, and checked.

The same tape covers character creation. “Deal me a character” rolls a legal starting character off the campaign seed. Guided creation walks the system’s real chargen sequence step by step, and even there the GM draws from the tape and shows its work.

What’s on the shelf.

Two systems ship built in. Cairn, Yochai Gal’s lean OSR game, digested from the Cairn 2e SRD under CC BY 4.0, with the attribution carried in the prompt itself. And Everything Is Dolphins, which needs a disclosure: it is my own game, written and self-published in 2012. You play a dolphin, the checks are d8s, and artifacts must be worn rather than carried because dolphins have no hands. The house system, included by its author.

Built in means enforced from the first roll. The table carries a pre-digested rules summary, and every turn passes a per-system validator: the character sheet’s shape is checked, and what the GM may change is bounded. A state update that rewrites your STR without a mechanical justification in the log gets rejected the same way a fudged die does.

Knave and Mausritter sit on the shelf marked coming. Their digests are auditable; the table machinery behind them, the dealt-character generator and the per-system validator, is not wired yet, and a system does not go live here without it.

The third tier exists because of licenses. Ironsworn, Old-School Essentials, and Worlds Without Number appear as links to the authors’ own free releases, not as built-in systems. Those licenses do not permit taking the text, digesting it, and re-serving it behind a paid subscription: Ironsworn’s full book is licensed non-commercial and only its smaller SRD subset is open enough to build from, OSE’s SRD carries share-alike obligations, and WWN’s free edition is a promotional excerpt of a commercial book. So the shelf says what it can honestly say: bring your copy, and here is where the author gives it away.

Sitting down.

Two ways in. Deal me one and sit down is the default: pick a system, get a legal character rolled off the tape, and be playing inside a minute. Create at the table opens session zero instead, and the GM walks the system’s actual creation rules in the system’s own order, rolling each attribute from the tape in front of you.

The table keeps state in a database, not in the model’s memory. Each turn the GM receives the rules digest, your current sheet, a short window of recent events, and the dice tape. Never the whole transcript. That is why there is no amnesia at turn eleven, and why a long campaign’s turns do not get slower or costlier as the log grows. Reopen a campaign and you get a “Previously at the table” recap generated from the event log.

The input bar has a Rewind button. It removes the last adjudicated turn and restores the prior state snapshot, so if the GM misreads what you said you did, you pull the turn back instead of arguing with it. Starting a new campaign while one is live asks first and never deletes the old one; every campaign stays resumable from the picker. And death gets an epilogue rather than an error state, with a path to raise a new character in the same world.

What it costs.

Nothing new. RPG GM mode is included with every paid plan: Basic at $4.99 a month, Regular at $9.99, and the founding Lifetime seats. No separate SKU, no add-on. It is subscriber-only; unlike the wargame modes there is no free demo tier at this table. The same token from your subscription email unlocks it alongside everything else. Each campaign carries a daily table budget with a quiet meter at the table, the same cost posture as Chat’s per-conversation cap. Current plans are at hammerstein.ai/#pricing.

If you subscribed months ago and drifted, this is a good week to sit back down. The modes you knew got a stronger model underneath, and there is a new table in the back room.