OnePlus is gradually moving away from CyanogenMOD and they are building their own ROM that’s based on the latest Android 5.0 Lollipop.
From an official posting at OnePlus forum, the upcoming ROM will be called OxygenOS, which promises to be open, customisable, and free of bloat and unnecessary features. This falls in line with its OnePlus One approach of having a device that’s powerful and straight forward without the unnecessary clutter. The reason behind the Oxygen name is because of its simple and pure nature, which OnePlus says its a fundamental building block.
They have yet to announce its official roll out dates but they would make another announcement on the 12th of February, which is just 2 weeks from now.