# Simulators — profiles of systems adjacent to clay-borg

Persisted research, not a link dump. Each profile answers the same
questions in the same order so the systems can be compared, and each
carries **what we actually checked**.

Written for [`../specs/Positioning.md`](../specs/Positioning.md) §1 and
§4 — the field we sit in, and the three tracks. Track A (a second game)
and Track B (game theory as the lens on dynamics) both depend on knowing
what already exists.

---

## The confidence rule

> **Every claim in a profile carries its source, and a claim from
> background knowledge is marked `unverified`.**

This directory was written immediately after three adversarial review
rounds whose entire yield was claims that outran what had been checked
([`../reviews/`](../reviews)). A profile that quietly mixes a fetched fact
with a half-remembered one is the same failure in a new place — and here
it would be worse, because these profiles are meant to inform whether we
build something or adopt it.

| marker | means |
|---|---|
| **`checked`** | read from a source this session, cited at the foot of the profile |
| **`unverified`** | from background knowledge; plausible, **not** confirmed, and must be before it decides anything |
| **`open`** | a question we want answered and did not answer |

## The schema

```
# <name>
owner · first release · licence · language          (checked/unverified)
## What it optimises for
## How a game is defined
## What it can analyse
## What it does not do
## Relevance to clay-borg      — which track, and how
## What to steal
## What to avoid
## Open questions
## Sources
```

## Index

| profile | in one line | track |
|---|---|---|
| [`ludii.md`](ludii.md) | the closest relative: ludemes, breadth, speed — **syntax formal, semantics is its Java** | A |
| [`gdl-ggp.md`](gdl-ggp.md) | the academic ancestor; agent generality over designer support | A |
| [`rbg.md`](rbg.md) | regular boardgames — a speed-focused rival description language | A |
| [`ai-ai.md`](ai-ai.md) | **the closest relative for what we want to become**: GGP with designer-facing metrics | A, C |
| [`openspiel.md`](openspiel.md) | the game-theory workbench: CFR, exploitability, social dilemmas | B |
| [`browne-criteria.md`](browne-criteria.md) | not a simulator — the canonical attempt to measure whether a game is *good* | C |
| [`machinations.md`](machinations.md) | economy and feedback loops, diagrammatic | — |
| [`play-substrates.md`](play-substrates.md) | Tabletop Simulator, boardgame.io — play without analysis | — |

## The formal question, answered

**Is there a game-theory mapping to Ludii's language, and is that language
formal enough to derive one from?**

**Yes to the first, no to the second, and the second does not matter.**
Ludii's universality result grounds it in **finite, non-deterministic,
imperfect-information extensive-form games** — the same object OpenSpiel's
CFR and exploitability consume. Ludii's *grammar* is formal (derived from
its class hierarchy) but its *semantics are its Java*, so there is no
independent calculus to extract.

**Conclusion: target the extensive-form game directly, not a language
derived from Ludii.** Worked through in
[`../research/CB-RES-0009-extensive-form-is-the-lingua-franca.md`](../research/CB-RES-0009-extensive-form-is-the-lingua-franca.md).

## What this survey has already changed

**Ai Ai and Browne's criteria are the finding.** Track C was written in
`Positioning.md` as though "assimilate knowledge about why games work"
were open ground. It is not: **Browne published 57 criteria for game
quality**, and Ai Ai already computes designer-facing measures — drama,
lead changes, branching factor, completion, duration — from played games.

That does not close Track C. It moves it from *invent* to *adopt, credit,
and find the gap*, which is a much better position and a much smaller
claim than the one we were about to make.