From Samuel Attard:
Google Play Music Desktop Player is a beautiful cross platform Desktop Player for Google Play Music. Google Play Music Desktop Player is open source on GitHub this means you, the community, gets a say in all the features we implement and you can even get involved and help out. Being a lightweight, standalone framework we use far less resources than having Google Play Music open in a standard chrome tab. This frees up your computers resources to do things you care about, instead of wasting them on playing music. Google Play Music Desktop Player adds a level of customization that simply isn’t there in the web player. You can change your theme, customize the colors, send your play history straight to last.fm, and it even has a built-in equalizer. From advanced audio controls to simple song change notifications, this desktop player literally does it all.