OnePlus is continuing its efforts to merge HydrogenOS and OxygenOS into a single, unified build of Android. There are new community builds of OxygenOS for the OnePlus 3 and OnePlus X. Neither one includes a jump to Nougat, but there are some new features.
The OnePlus 3 update (3.5.2) is 1.3GB in size and consists of the following.
Added “kill all background processes” button in recents menu
Added long press options in messages application
Enhanced incoming call notification UI
Added manual “check for update” button
Added additional directions for first fingerprint configuration
Battery Saver mode optimizations and enhancements
Added back contacts widget in launcher
Improved dialer speed
New modes added in control panel (night mode and battery saver)
Added support for PIN codes up to 6 digits
I do have some concern regarding that “kill all background processes” button. Seems like a good way to break things. If you're one of the few with a OnePlus X, your update to the community build (3.1.1) is only 761MB and includes a smaller list of changes.
Added ability to move apps to SD card
Improved touch responsiveness, speed, and accuracy
Improved HFR setting in video capture
Implemented September Android security patches
General bug fixes
To install, download the correct file and put it on your device's internal storage. Reboot into recovery, select your language, and install the update from "local." If you're using TWRP or some other recovery, the steps will vary. As usual, this is pre-release software. There will be bugs and secure features like Android Pay probably won't work.