# GDL / General Game Playing

Stanford Logic Group · `unverified` for current status · `checked` for the
Ludii comparison

## What it optimises for

**Agent generality**: an agent that plays a game it has never seen, given
only the rules in a logical description language.

## How a game is defined

**GDL** — a declarative, logic-programming description of legal moves,
state update and terminal conditions. Verbose relative to Ludii.
`checked` (verbosity claim from the Ludii comparison)

## What it can analyse

Little by design. GGP is a competition framework for agents; the game is
input, not subject.

## What it does not do

Anything designer-facing. **Ludii is measured as materially faster** —
more than six times for Gomoku 15×15, more than twenty for Amazons and
Hex, and over two hundred for Chess. `checked`

## Relevance to clay-borg

**Track A, as the cautionary case.** GDL is the purest form of "define
any game formally" and its cost is speed and readability. It is the
argument for *not* reaching for maximal generality first.

## What to steal

The separation of **rules-as-data** from the agent, which our kernel has
in a weaker form (rules are Rust; only the edition is data).

## What to avoid

Its verbosity, and its framing of the game as an input to an agent rather
than as an artifact under study.

## Open questions

- Whether GGP is still active, and where the community went.

## Sources

- *A note on the empirical comparison of RBG and Ludii*
  (https://arxiv.org/pdf/1910.00309)
- *Game Description Languages: the Good, the Bad, and the Ugly*, Björnsson
  (https://ludii.games/TalksWorkshop/Bjornsson.pdf)