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 reestablished as NetherRealm Studios. The original three games and their updates, Mortal Kombat (1992), Mortal Kombat II (1993), Mortal Kombat 3 (1995), Ultimate Mortal Kombat 3 (1995), and Mortal Kombat Trilogy (1996), are 2D fighting games. The arcade cabinet versions of the first two used a joystick and five buttons: high punch, low punch, high kick, low kick, and block; Mortal Kombat 3 and its updates added a sixth "run" button. Characters in the early Mortal Kombat games play virtually identically to one another, with the only major differences being their special moves. Through the 1990s, the developer and publisher Midway Games kept their single-styled fighting moves with four attack buttons for a different array of punches, kicks and blocks. Mortal Kombat: Deadly Alliance was the first Mortal Kombat game in which the characters could move in three dimensions, and Mortal Kombat 4 was the first to use 3D computer graphics.