The game hasn't come out yet but it seems sounds good. It's basically this: N. and S. Korea has joined together and have started annexing countries like Indoniesia, Thailand, and Phillipenes. They then EMP and invade the USA. Here's a timeline from Wikipedia:
2010: The South Korean corvette ROKS Cheonan was sunk by North Korea. 2011: North Korea faces another UN sanction over its latest nuclear test. 2012: Kim Jong-il passes away, succeeded by his son Kim Jong-un. 2013: Kim Jong-un is awarded the Nobel Peace Prize and featured on the cover of Time magazine for his accomplishment of Korean reunification. 2014: American military withdraws from the Korean Peninsula. A major US auto maker declares bankrupty for the second time. 2015: The effects of peak oil are felt as gas prices reach up to 20 dollars a gallon. Survivalist literature becomes best seller. China's influences diminishes. 2016: America withdraws its military from Japan and overseas, focusing on its instability back home. Texas separatism begins, border bloodshed takes place as refugees from other states attempt to enter the southern state. 2017: Martial law is declared in the United States as its infrastructure crumbles due financial difficulties. 2018: Korea occupies Japan. The UN is powerless to act. 2019: The UN is defunct. 2020: Canada closes its borders to Americans. 2021: Korean forces succeeded in annexing the countries of Malaysia, Brunei,Burma, Indonesia, Phillipines, Thailand, Cambodia, Laos and Vietnam. A new pandemic known as the Knoxville Cough begins to spread in the United States. 2022: Mexico closes its borders to Americans. 2023: The new flu ravages the American public. The Korean People's Army reaches 20 million. 2024: The Greater Korean Republic starts launching their own satellites, claiming to replace the collapsing GPS system originally launched by America. 2025: A Korean satellite decimates the American power grid through the use of EMP. This is followed by the Korean seizure of Hawaii and landings in San Francisco. 2026: The United States is split into two as Korean occupiers irradiate the entire Mississippi River and occupies the Western side. 2027: Homefront takes place.
I just learned that Homefront comes out on March 8, 2011 for North America. The game will have online gameplay, but I think it's only vehicle. (32 player games though!)