Virtua Fighter 4 is a fighting game developed by Sega AM2 and release by Sega for Sega NAOMI 2 arcade hardware in 2001. It is the fouth major entry in the Virtua Fighter series and a direct sequel to Virtua Fighter 3. The game was originally announced under the working title of Virtua Fighter X, before appearing with its final name at AOU Show 2001. The game changed the Japanese arcade landscape due to use of internet and physical cards to save progress, which was the VF .NET (later ALL.Net) system. The NAOMI 2 arcade version of Virtua Fighter 4 uses up to 20,000 polygons for each character, while each background uses over 50,000 polygons, with up to 16 hardware light sources per polygon, at 60 frames per second. This was the highest character polygon count and lights per polygon for a video game up until 2001, giving it the most detailed character graphics and lighting effects of its time (such as dynamic search lights). In comparison, the same year, Dead or Alive 3 on the Xbox used 10,000 to 15,000 polygons for the characters. Virtua Fighter 4's character polygon count was unsurpassed until Virtua Fighter 5 in 2005. In terms of textures, the game uses 128 MB of texture data for the characters. The PlayStation 2 version of Virtua Fighter 4, due to hardware limitations, reduced the polygon count down to 7,000 polygons for the characters and had much fewer light sources. The texture details were also reduced for the PlayStation 2 version.