Early this month Nickelodeon released part of the first Legend of Korra game. Unlocked at the time was only parts 1, 2 and 3 of a total of 9 parts to be released in the coming weeks. The game is fairly basic, allowing us to learn small bits of background information and explore new parts of Republic City. If you haven't already checked it out and you would like to, I've placed a link at the bottom of this post. Anyway, I'll try my best to highlight everything new that we can pull from parts 3, 4 and 5 which were released on the 20th of April.
- Central City Station - It is most likely located (or at least used to be) roughly in the center of Republic City. It is the major train station for all of Republic City.
- Zuko Statue - A statue of Zuko was placed in the middle of Central City station to remind citizens of Zuko's accomplishments made towards building Republic City with Avatar Aang. According to the statue Zuko stepped down from Fire Lord three years ago and handed the position over to his daughter. Zuko now travels the world as an ambassador for world balance. So apparently more of Team Avatar is still alive rather than just Katara?
- Republic City Currency - As we already knew, the official currency used in Republic City is called 'Yuan'. Yuan's are available as coins and paper bills. The paper bill features a picture of Avatar Aang on the front and a picture of City Hall on the back.
- Hiroshi Sato - Hiroshi Sato is the founder of Future Industries. He is the inventor and mastermind behind "Satomobiles" which are the Avatar Universe's version of cars.
- Satomobile - Before the invention of the Satomobile, engines relied on steam. Hiroshi was the first person to popularly develop a gasoline-powered engine.
- Naga - As revealed in part 6, Naga is the first polar bear-dog to ever be tamed. Before Korra managed to tame Naga, polar bear-dogs were feared and hunted in the Southern Water Tribe.
- Skoochy - Skoochy is child living on the streets of Republic City who knows both Mako and Bolin from when they lived on the streets of Republic City. He is a cunning and crafty kid who has escaped the two orphanage's he previously stayed in and choose to live a life on the streets instead. Skoochy is commonly found hanging around Central City Station pickpocketing tourists. He'll be happy to give people information if they are willing to pay for it.
If there's anything else I've missed which you feel I should add, leave it in a comment and I'll add it to the list once I read it. Other than that, hopefully this has been helpful. ^_^