The Necronomicon is a Web Application (PWA), you can use it within your browser like any normal website, but you can also add it to the Home screen of your mobile device like any other app:

iOS Safari

  1. Tap the Share icon in the bottom bar.
  2. From the menu, choose Add to Home screen
  3. Tap Add to confirm.

Android Browser

  1. Tap the icon on the top right of the browser.
  2. From the menu, tap Add to Home screen.
  3. Tap Add to confirm.

Chrome Desktop

  1. Click the Install Share button on the right of the address bar.
  2. Click Install to confirm.