Console: Mega Drive
Discontinued in: 1998
Sega's first big success actually flailed for a while in Japan before soaring to great popularity elsewhere after Sonic the Hedgehog dethroned Mario. Far and away Sega's most popular console, it was known in the US as the Genesis, presumably due to a trademark dispute with Mega Drive Systems, Inc. Fascinating!
Discontinued in: 1998
The US Mega Drive. At one point it was so successful it actually had Nintendo on the defense with a constant 50/50 handle on the market. This was achieved via savvy marketing (Genesis Does What Nintendon't), near arcade perfect games (Altered Beast, Space Harrier) and deals with celebrities (Michael Jackson, Joe Montana, Buster Douglass). It all made Sega seem like the cool console and Nintendo the kiddie system.
This is where the term "console war" really got going - people would get in actual fights (including some then-children GR editors) over this stuff. It wasn't until Sega went batshit insane with the near-simultaneous releases of Sega CD, 32X and Saturn that it started to lose control of the market, eventually ceding to the SNES.
Discontinued in: 1994
Interesting, this one. Lynx came out roughly the same time as the Game Boy, had a color screen and superior visuals, yet failed miserably, with less than a million units sold to date. Goes to show that all the hardware in the world can't make up for lack of games, something both Game Boy and Game Gear had in abundance. Cat names would eventually spell the end of Atari, as both Lynx and Jaguar are little more than humorous footnotes, even with fairly active homebrew audiences.
Console: Game Boy
Discontinued in: 1999
You're looking at one of the most successful, popular and long-lived gaming machines of all time. In addition to the backwards-compatible Game Boy Color, it's sold nearly 120 million units since its 1989 release, with several colors and limited-edition variants spicing thing up in between. Yes, it had fugly, blurry green graphics that looked kinda crappy even then, but its battery life and software support were so impressive you couldn’t not own one. This little machine also supported multiplayer via link cable, spawned the very first Pokemon game in 1996 and was initially bundled with Tetris - perhaps the smartest move Nintendo has ever made.
Discontinued in: 1990
The first of many, many bizarre revisions to the TG-16, this one had mildly altered innards and never left Japan. There were only seven games developed specifically for it (it also played older PC Engine and CD games) and it quickly faded away. Bring on the TurboDuo!
Jun 18, 2008