Magento Community Edition 1.x Mirror Github Repository
If you do not know what Composer is, please read this first.
To generate composer.json and install magento for the first time run:
composer require magento-hackathon/magento-composer-installer ~3.0
composer require aydin-hassan/magento-core-composer-installer ~1.2
composer require codephunk/magento ~1.9.4.5