It is no secret that smartphone manufacturer OnePlus has had a falling out with its initial software supplier Cyanogen. The public spat over the CyanogenMod 12S update delay has led the company to go ahead and develop its own ROM.
OxygenOS is now available to download for owners of the OnePlus One, and it should make many owners happy as it will be an upgrade to Lollipop. It is based on Android version 5.0.2 and has and has been worked on by some of the members of the Paranoid Android ROM team. Unfortunately, OnePlus missed its self-imposed March 27th deadline, but hopefully the extra time will mean that there are fewer bugs for those who update to the ROM.
Source: Android Police