Four players. Zero builds.

Why it matters

• No player builds. Ownership, prediction, join order and disconnects need real clients. You get them without a build, several copies or alt-tabbing.
• Four players, one change. A fix or a prompt reaches the primary and all three clones, and one handle call starts every player on the same frame.
• Seconds to boot. Clones share your Library, so nothing re-imports.

Real clients

Each extra player is a real hidden Unity editor that shares your Assets, Packages and Library, so a clone boots in seconds. Each has its own stream, console and input, and the primary's hot-reload and scene changes reach all of them. One Play button starts the grid.

Agents change all players at once

Through satura_exec on the Unity MCP server, an agent adds players and enters Play Mode on all of them. Your handles then run on one player or every player on the same frame:

[SaturaHandle("Jumps, and returns the height reached")]
public static float Jump() { ... }

// satura_exec
await unity.addPlayer()
await unity.play('Assets/Scenes/Arena.unity')
return await handles.call('Jump', { player: 'all' })
  → [{ player: 1, status: 'done', value: 2.1 }, { player: 2, status: 'done', value: 2.1 }]

Each player reports its own result, and SaturaHandles.PlayerIndex tells a handle which player it is. The agent reads the results, fixes what broke and runs it again. The report shows you the recorded match.