Capcom vs. SNK 2: Mark of the Millennium 2001[a] is the sequel to the fighting game Capcom vs. SNK. It was originally released on NAOMI hardware in arcades. As in the original, players select a team of fighters from various Capcom and SNK games then fight other teams, winning each battle by defeating all the opponents from the other team. Aspects of the first game were tweaked, including the Ratio system. In contrast to the fixed system of the original, players can now freely select characters and assign each of them a number from one to four (or "Ratio") determining their relative strength, adding up to a maximum team ratio of four. Teams can now consist of a maximum of three characters, as opposed to four in the first game. Additional characters were added, including more characters from Capcom and SNK titles outside of the Street Fighter and King of Fighters series, for a total of 48. The Groove system from Millennium Fight 2000 has been augmented to include four new systems of play based on various Capcom and SNK fighting games. In addition, the number of buttons has been increased from the Neo Geo standard of four to the six button system first seen in Capcom's Street Fighter. The console versions of the game were first released in Japan for the Dreamcast and PlayStation 2 on September 13, 2001 (just a month after the initial arcade release). Players from both platforms could compete against each other online via KDDI's Multi-Matching service, making Capcom vs. SNK 2 the first game ever to support cross-platform play between two competing game consoles.[5] The PS2 version would be released a bit later in other regions, but without online support. The GameCube and Xbox received an updated version titled Capcom vs. SNK 2 EO, with "EO" standing for "Easy Operation", referring to a game option intended for novices to the game. The Xbox version had online multiplayer support. The PS2 version was later released as a downloadable "PS2 Classics" game for the PlayStation 3 in July 2013.