If your 2015 was anything like mine, it passed by extremely quickly. It was marked by periods of frustration (spammers still love Drupal.org) and elation (Drupal 8 launched, woot!).
Below are a few highlights from our 2015 change logs on Drupal.org. For a more detailed look into each monthly update you can read our "What's New on Drupal.org?" blog posts.