HTC One M8 features a 5-inch 1080p display, 2.3 or 2.5 GHz Snapdragon 801 CPU/GPU, 2GB of RAM, enhanced “BoomSound” speakers, a 2600mAh battery, up to 32GB of internal storage and support for external microSD cards up 128GB. One of the most unique features of the HTC One (M8) is its new “Duo Camera.” This camera features two sensors: one Ultrapixel sensor and one depth of field sensor to allow users to select the image focus after the picture has been taken.
CyanogenMod team have created an updated nightly of CM 13 for HTC One M8. This will update One M8 to Android 6.0.1 Marshmallow. If you want to install this ROM, a detailed guide is given below.