Yep, this is the new G3 Keyboard and this app is designed to allow the G3 Keyboard to work only on the G2, the credit for this port goes to Cloudyfa. I don't have a G2 to test this but would be curious to hear about the results, please post, as the notable software features of the LG G3 is its Smart Keyboard that reduces input errors by up to 75% by tracking and analyzing typing habits and intuitively knowing what word the user intended to type. Enjoy!
Link for G3 to G2 Keyboard
Link for G3 to G2 Keyboard