After OnePlus fell out with Cyanogen, the manufacturer announced that they would be making their own Android-based custom ROM which they named Oxygen OS. The new OS was delayed but it is ready now, just about a week behind schedule.
This initial release of Oxygen OS is based on Android 5.0.2, so it is quite up-to-date. That might explain the slight delay too. It features screen-off gestures like double-tap to wake, music controls, and shortcuts for the camera and flashlight, and an improved file manager, among others. OnePlus say that Oxygen OS will focus on the things that matter most and not be bogged down with bloatware. Sounds good to us here.
Users of the OnePlus One can download and flash Oxygen OS to their device right away. Download Oxygen OS.