It’s the phone that refuses to die, so in a way, we’re not surprised someone managed to shoehorn Marshmallow onto the HTC HD2 (Leo). The phone has received just about every major Android update in one form or another and a few weeks ago, it apparently received another.
Still in an extremely early state, this new alpha build of CyanogenMod 13 has more than a handful of things that don’t properly work on it. Definitely not something you’re going to want to use as your daily driver but then again, even if you still have one of these phones in your possession, it’s more than likely not your primary phone anyway.
Still it’s a testament to the flexibility of the platform and prowess of Android developers on XDA. Just be careful. A wise doctor once told me, “Your scientists were so preoccupied with whether or not they could, that they didn’t stop to think if they should.”