[G2 Original Android Development] dr4stic:
Build Usage Notes:

I DO NOT give any guarantees on this working. PLEASE make a full backup before installing this zip. This rom comes with ABSOLUTELY NO SUPPORT (that's right, I don't really care if it works or not). That being said, I hope it works for you and you enjoy it :)

I'm so confused! The last official nightly was from Nov-2015, how in the world could this be current?!?:

The CyanogenMod devs didn't stop developing on version 12.1 when we were transitioned to 13.0. There was a period of months where a group of developers started transitioning existing features and developing new features on CM-13.0, while another group worked to continue to stabilize and maintain the existing CM-12.1 codebase. Sadly, we were one of the very first devices transitioned to 13.0 at the very beginning of the 13.0 development. Therefore we never received a particularly solid 12.1 build.

These builds represent a nightly build from the continually developed 12.1 code base. It has a large number of fixes that have occurred (and, at a very slow pace now, continue to occur) from November of 2015 to the present. Additionally this build has all the monthly security patches from google. These are incorporated by CM, not me. With the exception of the Sprint(US) model of the G2 (the LS980), these builds represent the most up-to-date official builds of CM-12.1 for the G2 you will find.

What are the requirements and/or procedure for installing this ROM?:

These CM-12.1 builds are essentially the same as the official and nightly CM-12.1 builds. Therefore the requirements are the same. Please visit the Official CM-12.1 XDA Thread for information on the requirements and procedure on installing this ROM.

NOTE: This is my own personal recommendation. I HIGHLY recommend following the advice from the CM-13.0 builds: if you can, if you have the chance, backup your device and copy that backup and your phone data to your computer, then completely wipe your device. Do a full stock update (KDZ, TOT, forced OTA's, whatever) to bring your device up to stock LG Lollipop. From there, root the device, do the auto-rec, update TWRP to the latest from blastagator, and then install this ROM and a compatible Gapps package. I personally believe putting your device on stock lollipop firmwares will give you the best possible experience on a Lollipop ROM. And whatever you do, DO NOT USE BOOTSTACKS!!!

Flashing over official CM-12.1:

As stated above, these builds are essentially the same as the official and nightly CM-12.1 builds. They aren't substantially different enough to cause compatibility problems. They are simply updated builds with a number of fixes, and the only real added package is the Snap from CM-13.0. You *should* be about to simply flash this over an existing official CM-12.1 build (which I recently did over a 7-8 month old build with no ill effect).

That being said, if in doubt, do the appropriate backups and start fresh from scratch, restoring app data as necessary. Often times a fresh install can solve a number of odd problems and lead to a smoother experience.

I have a newer nightly, I just want the Snap camera:

If you are currently on the Sprint LG G2 (The LS980) you are already on the official CM-12.1 track, and any future official nightlies will incorporate the IR and Volume patches from my 20160614 builds. Otherwise if you like the nightly you're on and you really just want the snap camera, you can download them here:

Download: Snap camera for CM-12.1 G2 Builds

These zip files should be installed via the recovery. They are also persistent, you won't need to flash them every time you update the ROM. You will only need to re-install whenever you do a clean reset of the device. I will try to upload a new build of Snap whenever I build new snapshots.

Note about Snap builds: Because the Snap settings aren't integrated into the ROM itself, I don't believe these Snap builds will have working HDR. I'm not sure, but if it doesn't work there's nothing really I can do about it.

Can I safely use the CM Updater?:

In a word: No. The only exception to that is if you are on the LS980 device. The recommended way to update these builds is by manually downloading them and flashing them from TWRP (or your chosen recovery).

The CM Updater downloads updates from CM's official build system. For most G2 devices CM Updater will offer you CM-13.0 builds to update to. If you try to update to a CM-13.0 release through the CM Updater from CM-12.1, your device will cease to work. Your best bet (and my recommendation) is to go into the updater (Settings -> About Phone -> System Updates) and setting the update type to "Manual". That will keep the device from checking for updates. Another option would be to re-install your gapps and set it to remove the CM Updater all together.

If you are on an LS980 device, the CM build system is providing you relatively up to date builds. You should be able to use CM Updater to safely update from one of my releases to a newer official CM nightly without any trouble. The only thing you will lose is the Snap camera. In this case I would recommend staying with the official nightly and simply installing the Snap camera separately as mentioned above.

My device seems to be heating up:

User [MENTION=3483844]mwedo[/MENTION] on the official thread had a similar problem (click here to see). He tracked it down to the "OK Google" Hotword detection. After disabling it his device things returned to normal. I don't know why this happens, and I doubt it'll get fixed in my lifetime since 12.1 is no longer on the support track for us. However, I am mentioning it here for those of you experiencing a similar problem. I have also updated the gapps-config attachment that I posted below to disable the default Hotword enrollment. Hopefully that'll save people some headache. The gapps-config keyword is "Hotword".

IMPORTANT: Gapps / OpenGapps and Snap Camera:

If you use a modern-ish Gapps package, it may recognize Snap as the default CM camera and remove it. You should modify your Gapps config so that it does NOT do that. If you need to modify Gapp's behavior, you can wipe the system partition (do NOT factory reset), and then fresh install your ROM and Gapps (with any gapps-config modifications you need). I am attaching the gapps-config.txt file I use in conjunction with OpenGapps "Stock" release. Keep in mind it removes the built in Gallery to be replaced by Google Photos.