Sudden Attack (Korean: 서든어택) is a free-to-play multiplayer first-person shooter online game developed by the South Korean company GameHi. The North American service for Sudden Attack was terminated on January 29, 2014. A sequel, Sudden Attack , was launched in 2016. By June 2020, the game had over 23 million registered users worldwide and grossed over $500 million in lifetime revenue.[1] By December 2021, the game grossed over $600 million.[2]