In ancient Greece, Apollo was—among other things—the god of music. In ancient 2012, Apollo became the official music app for CyanogenMod. It was gorgeous, functional, and completely customizable, as you might expect from the world's most popular ROM. At the time, we were told that this lovely bit of software would be coming to the Market "in the coming weeks." That was back when we still called it the Market. Today, though, Apollo is available on the Play Store.
The player comes in two flavors: regular, and +. Apollo+ removes ads and offers quicker updates for a mere $0.99. On the subject of future updates, there are a number of features that are promised to come soon, including tablet support, concert info, customizable widgets and notifications, and "Google Dream" (we suppose they mean Daydream) support. For those wondering, gapless playback isn't a planned feature, it's a current one. Hooray!
You can grab either the free Apollo or the $0.99 Apollo+ via the widgets below. If you're running CyanogenMod, the player probably came bundled as a stock app. If you want to install this one for whatever reason, you may need to disable the stock app in Settings, or live with two identical icons in your drawer.