If you own an OnePlus One device and you’re eager to update it to the Android 6.0 Marshmallow version, then you should consider downloading and installing the custom ROM of this operating system created by PAC-man.
We remind you that this is an experimental build, as the custom ROM is directly compiled from PAC ROM github and it doesn’t have any additional customization. For now, the custom ROM doesn’t have any major bugs reported, but if you want to sync your mobile device with your computer, you will most likely need to change from USB charging to file transfer. To do this, you will just need to swipe down from the top side of the home screen and select the “File Transfer” option (after connecting your mobile device to your computer).
At the same time, if you want to gain root access to your OnePlus One device, you will not need to flash SUperSU or use any other root package, as you will be able to enable the Developer settings by tapping on the build version information a few times and activate “Root” access.
Installing Android 6.0 Marshmallow PAC-man ROM On Your OnePlus One Device
First of all, you will need to download the Android 6.0 Marshmallow Pac-man ROM and Gapps zip files to your computer. Connect your OnePlus One device to your computer and copy the Android 6.0 Marshmallow Pac-man ROM to your OnePlus One device.
Unplug the OnePlus One device from your computer and turn it off. Now boot it into recovery mode by pressing and holding the Power and Volume Down buttons.
Once the device boots into recovery mode, you will need to make a backup of all the data from your device and after that perform a full data wipe by selecting Wipe->Advanced Wipe and choose: Data, Cache and Dalvik Cache.
Once all data is wiped from your OnePlus device, go back to the main recovery menu and select “install zip from sdcard”. Now, go to the location where you’ve saved the Android 6.0 Marshmallow Pac-man ROM and install it on your device. Do the same with the Gapps zip file and once this file is installed, go back to the main recovery menu and select “reboot system now”.