Less than a fortnight after OnePlus released OxygenOS to give OnePlus One users the first official taste of Lollipop, Cyanogen Inc. has released its more feature-heavy Lollipop flavor named Cyanogen OS 12 for the flagship killer.

OnePlus co-founder Carl Pei had recently confirmed that the eagerly anticipated Cyanogen OS 12 update for the OnePlus One smartphone had received certification and would be rolled out within a few days.

Users of OnePlus One running Cyanogen OS have been worried about the consequences of the fallout between the Chinese startup smartphone manufacturer and Cyanogen late last year. Following its break-up with Cyanogen, OnePlus had been developing its own custom Android ROM, called Oxygen OS, which is designed to give almost a stock Android like experience, similar to that on the Nexus 6. Less than a fortnight ago, OnePlus finally released the new Oxygen OS for the OnePlus One after numerous delays and missing its self-imposed deadline.

Apart from its own version of Android for the OnePlus One, the company had also planned to release a new version of Cyanogen OS 12 for the OnePlus One. However, the company had failed to meet its March 30 deadline for releasing Cyanogen OS 12 featuring Android 5.0.2, due to certification issues.

Steve Kondik, chief technical officer at Cyanogen, in response to the delay over releasing the Cyanogen OS 12 update for OnePlus One stated through a Google post: "Seriously though, a new test suite came out because of MR1 literally the same day as we submitted, and so we had to redo the whole process with the new one."

Cyanogen has now announced that the Cyanogen OS 12 update has begun rolling out to "all" OnePlus One devices owners across the world, and is based on Android 5.0 "Lollipop," which includes many new features as well as a major user interface update based on Google's new "Material Design" philosophy. The Cyanogen OS 12 update also introduces some new features, including an App Themer for customizing the phone and an in-house email client based on Boxer.

OnePlus had promised two years of updates for its OnePlus One smartphone, which means that the Android 5.1-based Cyanogen OS 12.1 and the Android M-based Cyanogen OS 13 are also likely to follow soon.