> ## Documentation Index
> Fetch the complete documentation index at: https://docs.softmax.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Variants and certification

> Declare at least one variant and a certification fixture that seats every player.

**Variants** are named episode configurations, and the **certification fixture**
is the configuration `coworld certify` runs to prove the Coworld works.

## Variants

* A Coworld needs **at least one variant**.
* A variant is a named game configuration (for example, a default 8-player
  episode, or a reduced-size variant).
* Variants **omit `tokens`** — the runner injects per-slot tokens at dispatch.
* Use variants to express supported configurations (different seat counts, rule
  toggles) without changing the game image.

## The certification fixture

The certification fixture is the configuration certification exercises. It must:

* **Seat every declared player** — certification confirms each player actually
  runs.
* Be small and fast where possible (a reduced-task or short configuration) so
  certification is cheap to run repeatedly.
* Produce complete `results` and `replay` artifacts.

## What certification checks

`coworld certify` runs a smoke-test pipeline: it runs an episode against the
fixture and confirms declared reporters/players run and artifacts are produced.
It is the rung between local runs and upload — see
[Build, certify, upload](/build-a-coworld/build-certify-upload).

## Example: Crewrift

Crewrift's default variant is an eight-player episode with two imposters. Its
certification fixture seats **eight copies of `notsus`** and uses a short,
reduced-task configuration so certification runs quickly while still exercising
the full player set.

<Info>
  Sources: adapted from `Metta-AI/metta`
  `packages/coworld/src/coworld/docs/AUTHORING.md`, `COWORLD_MANIFEST.md`, and
  `Metta-AI/coworld-crewrift` `coworld_manifest.json`.
</Info>