The 2000s was the fourth decade of the video game industry. It was a decade that was primarily dominated by Sony, Nintendo, newcomer Microsoft, and their respective systems. Sega, being Nintendo's main rival in the 1980s and 1990s, left the console market in 2002 in favor of returning to third-party development, as they once were. Overall the decade saw the last of the low resolution three-dimensional polygons of the 1990s with the emergence of high definition games, and often focused on developing immersive and interactive environments, implementing realistic physics, and improving artificial intelligence. The sixth and seventh generation of video game consoles went on sale, including the PlayStation 2, Wii, Xbox, PlayStation 3, Game Boy Advance and Xbox 360. Notable games released in the 2000s included Half-Life 2, Wii Sports, Grand Theft Auto III, The Sims, Ikaruga, Tony Hawk's Pro Skater 3, Star Wars: Knights of the Old Republic, Batman: Arkham Asylum, Super Mario Galaxy, the Halo trilogy and Call of Duty 4: Modern Warfare. Consoles of the 2000s Sixth generation (1999–2006) The sixth generation of video games officially began in 1998 with the introduction of the short-lived Dreamcast, which was discontinued in 2001. Sega announced that they would no longer produce video game consoles after two straight underperforming consoles and became a third-party developer. The PlayStation 2 was released in 2000 and became the best-selling video game console of all time. Microsoft entered the home console market with the Xbox. Although initially expected to struggle, it managed to reach second place in sales behind the PS2 on the strength of the launch title Halo: Combat Evolved. The GameCube, launched in 2001 alongside the Xbox, fell into third place, a first for Nintendo. The sixth generation improved on the 3D graphics of the fifth generation consoles. Some of the new features in the consoles included built-in DVD players and hard drives. Internet play on consoles, pioneered by the Dreamcast, became commercially viable with the Xbox Live system, which was launched in November 2002, one year after the console's release. It featured a broadband connection and downloadable content and was a success. Seventh generation (2005–2012) The seventh generation of consoles began with the release of the Xbox 360 in 2005. This was followed by the Wii and the PlayStation 3 in 2006. The seventh-generation featured widespread implementation of HD-ready graphics, media centers, and wireless game controllers, as well as online services