# game_project_required

> `disko dev` was run in a directory without `game.json`.

| | |
| --- | --- |
| Kind | `disko` command error |
| `disko` exit code | 2 (usage) |

`disko dev` runs game projects: the directory it runs in, or the one given
with `--project`, must contain `game.json`. Without it, the command fails
with `game_project_required` and exits with code 2 before signing in.

A room project (created with `npm create @disko-game -- room`) has no
`game.json`; it runs with `npm start`, not with `disko dev`.

## Wrong

```sh
cd my-room
npx disko dev
```

## Right

Run it in the game project, or point `--project` at it:

```sh
npx disko dev --project ../arena
```

To try a room project's host function with `disko dev`, copy it into the
game project as `server.js`.

## See also

- [Test rooms (disko dev)](/get-started/test-rooms)
- [Project structure](/games/project-structure)