1. Tap the Share button — the square with an arrow pointing out of it. Safari keeps it in the toolbar at the bottom of the screen; Chrome, in the address bar.
2. Scroll down the list and tap Add to Home Screen.
3. Tap Add.

The game then opens fullscreen from your home screen, and plays offline.

1. Open the File menu and choose Add to Dock. It is also under the Share button in Safari's toolbar.
2. Confirm the name, and click Add.

The game then opens in its own window from the Dock, and plays offline.