The OnePlus thanks to very few models. The first OnePlus powerfully attracted attention for its special way of selling itself, since to acquire it you needed to have an invitation. These invitations were given with a dropper, and the attention for this phone went up almost exponentially, which caused it to spread like foam.
The OnePlus X is not a terminal that has been updated quickly, so this news, for those who have it in possession, is very satisfactory, since after almost a year in Lollipop, the terminal has already published the first build of OxygenOS based on Android 6.0.1 Marshmallow.
The only thing this ROM has been created by the community itself, which is not the typical official one that arrives by OTA. This means that you may have some performance and stability issues. You will have to flash it manually, so it is not a dedicated launch for the normal user, but you have to be used to this type of installation.
You can visit the OnePlus forums where you can find all notes in detail. OnePlus maintains that this build includes all the new icon packs, the new custom Google search bar, a new wallpaper picker, a couple of new apps (OnePlus Music Player and OnePlus Gallery), and much more.
The download is arranged from the own download page from OnePlus, and the company would appreciate that, those who have installed it, share the feedback about it. Also mention that this post is limited, which means that OnePlus may remove the download link at some point when it has received the necessary feedback.
It would be advisable to wait a bit to have a final version, although if you want to have marshmallow on your OnePlus X you are one step away from obtaining it.