Video games aren't just for kids. In fact, they are big business. According to the industry-tracking NPD Group, sales of games and consoles totaled more than $13 billion in 2012. With the recent introductions of the PlayStation 4 and the Xbox One, Sony and Microsoft are just the latest in a long line of companies competing for a piece of the pie. Take a look back at the consoles of the past.

Magnavox Odyssey
Release: 1972.
Units sold: 330,000.
Of note: Used plastic screen overlays for many games to simulate graphics the unit was not powerful enough to display.
Top games: Had 27 total.

Atari Pong
Release: 1975.
Units sold: 150,000.
Of note: Settled out of court for patent infringement over the game's similarities to Magnavox's "Tennis" game for the Odyssey.
Top game: "Pong."

Atari 2600
Release: 1977.
Units sold: 28 million.
Of note: Was the first highly succesful game console. Credited with popularizing interchangeable game cartridges.
Top game: "Pac-Man."

Intellivision
Release: 1979.
Units sold: 3 million.
Of note: Was the first console to feature downloadable games – but had no storage device to save them.
Top game: "Las Vegas Poker & Blackjack."

ColecoVision
Release: 1982.
Units sold: 1 million.
Of note: Offered near-arcade-quality graphics, and an adapter allowed it to play the entire Atari 2600 game catalog.
Top game: "Donkey Kong."

Nintendo Entertainment System
Release: 1985.
Units sold: 62 million.
Of note: Debuted some of the most popular franchises, including "Legend of Zelda" and "Final Fantasy."
Top game: "Super Mario Bros."

Sega Master System
Release: 1986.
Units sold: 15 million.
Of note: Was once distributed in the United States by ­Minnetonka-based toy maker Tonka.
Top game: "Alex Kidd in Miracle World."

Sega Genesis
Release: 1989.
Units sold: 42 million.
Of note: Later came with "Sonic the Hedgehog" to compete with Nintendo's popular "Mario" franchise.
Top game: "Sonic the Hedgehog."

TurboGrafx-16
Release: 1989.
Units sold: 10 million.
Of note: Featured only one controller port, unlike most other consoles.
Top game: "Bonk's Adventure."

Super Nintendo
Release: 1991.
Units sold: 49 million.
Of note: Had one of the first three-dimensional console games, "Star Fox."
Top game: "Super Mario World."

3DO
Release: 1993.
Units sold: 2 million.
Of note: Was named Time's Product of the Year in'94 but was hurt by its high price and lack of games.
Top game: "Return Fire."

Sony PlayStation
Release: 1995.
Units sold: 102 million.
Of note: Continued to have games produced for it for more than 11 years.
Top game: "Gran Turismo."

Sega Saturn
Release: 1995.
Units sold: 10 million.
Of note: Never gained traction in the U.S. market, although popular in Japan.
Top game: "Virtua Fighter 2."

Nintendo 64
Release: 1996.
Units sold: 33 million.
Of note: Was the last successful console to ship games on cartridges.
Top game: "Super Mario 64."

Sega Dreamcast
Release: 1998.
Units sold: 11 million.
Of note: Marked Sega's last home console after years of fierce competition.
Top game: "Sonic Adventure."

Nintendo GameCube
Release: 2001.
Units sold: 22 million.
Of note: Was Nintendo's first disc-based system; also played Game Boy cartridges with an adapter.
Top game: "Super Smash Bros. Melee."

Sony PlayStation 2
Release: 2000.
Units sold: 155 million.
Of note: Boasts the title of being the bestselling home game console of all time.
Top game: "Grand Theft Auto: San Andreas."

Microsoft Xbox
Release: 2001.
Units sold: 24 million.
Of note: Gained a foothold in online gaming and competed with established consoles thanks to a built-in ethernet port.
Top game: "Halo 2."

Microsoft Xbox 360
Release: 2005.
Units sold: 79 million.
Of note: Lets users play without a controller – using their voice and movements — with the 2010 Kinect add-on.
Top game: "Grand Theft Auto 5."

Sony PlayStation 3
Release: 2006.
Units sold: 80 million.
Of note: Was the only game console on the market at the time that could double as a Blu-ray player.
Top game: "Gran Turismo 5."

Nintendo Wii
Release: 2006.
Units sold: 100 million.
Of note: Was the first console to translate players' body movements into on-screen actions.
Top game: "Wii Sports."

Nintendo Wii U
Release: 2012.
Units sold: 4 million.
Of note: Has a controller with a touch screen that allows compatible games to be played without a TV.
Top game: "Nintendo Land."

Sony PlayStation 4
Release: Nov. 15.
Units sold: N/A.
Of note: Has 10 times the processing power of the already- powerful PS3, according to Sony.
Top game: "Call of Duty: Ghosts."

Microsoft Xbox One
Release: Nov. 22.
Units sold: N/A.
Of note: Aims to be an all-in-one entertainment center, with voice control — not just a game console.
Top game: "Call of Duty: Ghosts."

Source: Wikipedia, VGChartz