If you're a LG G2 owner and are craving for the G3's new and simplified software experience, you're in luck. Thanks to OptimusRs on XDA Developers, the software on LG's latest flagship device is available to install in the form of a custom ROM.
The ROM, which you can find right here, is available for all variants of the LG G2, though not all features work. For example, Knock Code works on my T-Mobile LG G2, but only while the screen is on, so I can't use the feature while the phone is in its sleeping state. Due to different kernel versions running on these variants, this won't change anytime soon, but a few can indeed use Knock Code to its full potential.
The ROM also gives the older G2's 4K video recording capabilities, along with the new Magic Focus feature found on the G3's camera, which should get some people excited.
Given that this ROM is version 1.0, there's a chance you could run into a few bugs along the way. The ROM's XDA landing page also has a helpful, albeit short, FAQ section. I've yet to dive deep into the new ROM for the G2, but so far, it seems snappy and stable.
Do keep in mind that to install this ROM, you'll need to be rooted and have a custom recovery installed.
Note: The ROM will not give you the weird, color-warped look found in the image above. My G2 suffered through a traumatic water accident.