Mortal Kombat is a media franchise centered on a series of fighting video games originally developed by Midway Games in 1992. The original Mortal Kombat arcade game spawned a franchise consisting of action-adventure games, a comic book series, a card game, films, an animated TV series, and a live-action tour. Mortal Kombat has become the best-selling fighting game franchise worldwide and one of the highest-grossing media franchises of all time. The series has a reputation for high levels of graphic violence, including, most notably, its fatalities, which are finishing moves that kill defeated opponents instead of knocking them out. Controversies surrounding Mortal Kombat, in part, led to the creation of the Entertainment Software Rating Board (ESRB) video game rating system. Early games in the series were noted for their realistic digitized sprites and an extensive use of palette swapping to create new characters. Following Midway's bankruptcy, the Mortal Kombat development team was acquired by Warner Bros. Entertainment and re-established as NetherRealm Studios.