# Positioning — what clay-borg is for, and what it does that others do not

Status: **draft**. A working answer to *"where does this sit, and what is
the point of it"*, written against the field rather than in isolation.

Companion to [`../INTENT.md`](../INTENT.md) (what we are building),
[`Taxonomy.md`](Taxonomy.md) (the vocabulary), and
[`Ornamentation.md`](Ornamentation.md) (the boundary). The systems named
below have profiles in [`../simulators/`](../simulators), each marking
what was checked and what is background recollection.

> **Revised 2026-08-08 after the survey**, and §4 changed. Two of the
> three tracks were described as more open than they are — see §4.0.

---

## 1. The field, honestly

There are mature systems here and we are not first.

| system | what it optimises for | what it does not do |
|---|---|---|
| **Ludii** (Digital Ludeme Project) | *generality of representation*. Games as **ludemes** — composable, human-readable concepts. Fast, broad, a game fits in a QR code | it is not built to argue with the designer about the rules, and its evidence is not auditable by a third party |
| **GDL / General Game Playing** (Stanford) | *agent generality* — an agent that plays a game it has never seen | verbose, slow relative to Ludii, and aimed at AI research rather than design support |
| **Machinations** | *economy and feedback-loop simulation*, diagrammatic and immediate | not rules-complete; a model of flows, not of a played game |
| **Tabletop Simulator / boardgame.io** | *play*, human or networked | no analysis; the rules are a script, not a claim |
| **RL self-play stacks** | *strength* | a strong agent tells you what beats what, not why a rule is undecided |

**Ludii is the closest relative and the right benchmark.** If clay-borg's
answer to *"why not Ludii"* is only "ours is in Rust", there is no answer.

## 2. What we do differently

Four things, and each is already visible in the repo rather than aspired
to.

### 2.1 The measurement is under suspicion by construction

Every other system in §1 treats its own output as data. **This one treats
its own output as a claim that has to survive an attempt to break it** —
`GameDesign.md` §1 admissibility, the finding register, mutation-proof as
a condition for a control, and mandatory adversarial review at tier L.

**This is not a posture; it is measured.** Three review rounds on one
measurement found twelve fatal defects, **every one in our instrument and
none in the game** — including two that inverted a verdict already written
down. A tool that reports game-design conclusions without that machinery
is reporting its own bugs at the same volume as its results.

### 2.2 Authority is federated, and the simulator is not the authority

The game's owner rules; we report. A rule we cannot execute becomes a
**finding** carried back with the artifact that produced it — never a
default we quietly pick.

**Ludii's model is a description someone wrote. Ours is a claim about
somebody else's artifact**, with digests and tripwires against their
source of truth, and a queue of open questions that belong to them. That
is a different relationship to the designer than any system above has.

### 2.3 What is *not* mechanism is modelled too

[`Ornamentation.md`](Ornamentation.md). Materials, ceremony, typography,
timing — declared, with falsifiers, and separated from the rules by a test
something can run (does the state hash move?).

Every system in §1 either ignores this or treats it as presentation
config. **We treat "this does not matter" as a claim that can be wrong**,
because our own register is a list of times it was.

### 2.4 A hypothesis is a package, not a patch

A design experiment arrives as a selectable variant — a catalog entry,
a machine-readable `rules_delta`, declared success criteria — and is
measured against those criteria, with the results reported including the
parts that fail. The variant is in the game state, so a recording says
which rules it was played under.

## 3. What that adds up to

> **Clay-borg is a design-evidence instrument, not a game engine and not a
> game-playing AI.** Its product is an auditable answer to *"what does this
> rule actually do at the table, and how much should you trust that?"*

The second half of that sentence is the differentiator. Anyone can produce
the number.

## 4. Where it has to go

Three tracks, in dependency order. None started.

### 4.0 What the survey changed

**Two tracks were overclaimed and are now smaller.** Writing the
[`simulators/`](../simulators) profiles found prior art where this
document had assumed open ground:

- **Track C is not open ground.** **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. The track moves from *invent a theory of fun* to **adopt
  an existing vocabulary, credit it, and locate the gap**. The gap is
  plausibly real (co-operative and hidden-role games), and it is a far
  smaller and more defensible claim.
- **Track B probably adopts rather than builds.** **OpenSpiel** implements
  CFR, best-response and **exploitability** over games that are
  simultaneous-move, imperfect-information and cooperative — all four of
  GROUND's awkward properties. *"Does ATTACK ever pay"* is a
  best-response question, and we have been answering it with two
  hand-written policies.

**This is what a survey is for**, and it is worth noting that the cost of
not doing it earlier was measurable: we spent three review rounds refining
a two-policy sweep for a question that has a standard instrument.

### Track A — a second game

**GROUND is an example, and nothing has tested that claim.** Every
abstraction here has exactly one instance, which by our own rule
(GameDesign §2) means it may have been invented rather than observed.

The work is to take a **popular, well-understood game** — one where the
dynamics are already documented, so our output can be checked against
something — and build a clay-borg definition efficiently enough that the
cost is itself the finding. **The measurement that matters is how much of
the kernel turns out to be GROUND-shaped.**

Ludii's ludeme decomposition is the obvious prior art to steal from, and
the honest question is whether we need our own description language at all
or should consume theirs.

### Track B — game theory as the lens on dynamics

§4 of [`Taxonomy.md`](Taxonomy.md): our panels measure **dynamics**, and
game theory is the science of exactly that. Today we sample the strategy
space with two hand-written policies and a rank parameter. That is a crude
instrument for questions that have real theory behind them:

- **dominance** — is an action dominated? (F17 asks this about ATTACK and
  answers it with a sweep)
- **equilibrium** — what does competent play converge to, and is it the
  play the designer intended?
- **cooperative solution concepts** — GROUND is co-operative with a
  defection mechanic; the **core** and the **Shapley value** are the
  standard tools for "is this coalition stable" and "what is a seat
  contributing", which is precisely what GR-E04 is groping at
- **social dilemmas** — DARVO is one; the literature on them is large

**The proposed shape is a specialised agent**, not a library: something
that reads a clay-borg game definition and a panel run, and reports what
the theory says about the dynamics — with the same admissibility rules as
everything else, because a Nash equilibrium quoted without its assumptions
is exactly the wrong-subject error in mathematical dress
([`Taxonomy.md`](Taxonomy.md) §2.2).

**But the first task is not to build it**, and the survey narrowed it
twice more ([`../research/CB-RES-0009-extensive-form-is-the-lingua-franca.md`](../research/CB-RES-0009-extensive-form-is-the-lingua-franca.md)).

**The formal object is the extensive-form game**, proven expressive enough
by Ludii's universality result and consumed directly by OpenSpiel — so
"Ludii → EFG ← OpenSpiel" is the whole mapping, and there is nothing to
invent.

**And we already have most of an EFG**: the journal is the history, the
payoff is `Outcome`, and **`project(Viewer::Player(seat))` is the
information partition** — built so a player is not shown another's hand,
and unremarked as the machinery imperfect information needs.

**Three gaps, one checkable today:**

1. **chance is folded into a seed**, so a clay-borg game is one
   realisation rather than a game with chance nodes;
2. **perfect recall is unasserted** — CFR and exploitability assume a
   player remembers their own past actions and observations, and nobody
   has checked whether our projection sequence does;
3. simultaneity is encoded by commit/reveal but never *stated* as the
   standard EFG encoding.

**Track B's first task is (2)**, because it is small, checkable from the
journal, and if it fails every equilibrium concept we might quote is
unsound here. That is a better opening move than a build.

### Track C — assimilated knowledge about why games work

The furthest out, and the one the maintainer named as the point:
**make what is known about game dynamics available to designers.**

MDA's aesthetics vocabulary, **Browne's criteria**, the balance
literature, documented failure modes (runaway leader, kingmaking, analysis
paralysis, dominant strategy, degenerate equilibrium). The value is not a
database — it is that a finding from a panel run can be **named** as an
instance of a known pattern, and the designer told what usually follows.

**And the gap is now visible.** The criteria that exist assume a leader:
*lead change* and *drama* are defined against who is ahead. **SHARED
GROUND has no individual leader** — `Modes.csv` gives its tiebreak as
"Not applicable" — so the canonical vocabulary does not reach the game we
have. Whether these measures extend to co-operative and hidden-role play
is the open question, and it is a better Track C than the one this
document originally proposed.

**The risk is obvious and worth stating now**: this track is where a tool
starts telling designers what is fun, on the strength of numbers that
measure dynamics. §4 of the taxonomy is the guard, and it will be under
pressure here.

## 5. Falsifier

**Track A is the falsifier for this whole document.** If a second game
cannot be defined without reshaping the kernel around it, then "GROUND is
an example" was never true, clay-borg is a GROUND engine with ambitions,
and §2's differentiators are properties of one bespoke tool rather than of
a framework.