Awesome

1. Clone the repo and get dependencies via composer

   git clone --depth 1 --branch master https://github.com/phpish/shopify_app-skeleton.git new_prj
   cd new_prj
   rm -rf .git
   rm README.md
   curl -sS https://getcomposer.org/installer | php
   php composer.phar install
   

2. Create your app. Use http://path-to-new_prj/oauth.php as the Callback URL

3. Get the app's credentials and update conf.php

4. Intall the app on a store by visiting http://path-to-new_prj/install.php?shop=example-shop.myshopify.com

5. An OAuth token for the shop should now be stored in the session. Check out the other .php files and see how they work.