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Tuesday, February 17, 2009

Space Invaders (Game)

Space Invaders​ (スペースインベーダー Supēsu Inbēdā?) is an arcade video game designed by Tomohiro Nishikado, and released in 1978. It was originally manufactured and sold by Taito in Japan, and was later licensed for production in the United States by the Midway division of Bally. Space Invaders is one of the earliest shooting games and the aim is to defeat waves of aliens with a laser cannon to earn as many points as possible. In designing the game, Nishikado drew inspiration from popular media: Breakout, The War of the Worlds, and Star Wars. To complete it, he had to design custom hardware and development tools.
Though simple by today's standards, with basic two-dimensional graphics, it was one of the forerunners of modern video gaming and helped expand the video game industry from a novelty to a global industry. When first released, Space Invaders was very successful and popular. Following its release, the game caused a temporary shortage of 100-yen coins in Japan, and by 2007 had earned Taito US$500 million in revenue. Guinness World Records ranks it the top arcade game.
The game has been the inspiration for other video games, re-released on numerous platforms, and led to several sequels. The 1980 Atari 2600 version quadrupled the system's sales and became the first "killer app" for video game consoles. Space Invaders has been referenced and parodied in multiple television shows, and been a part of several video game and cultural exhibitions. The pixelated enemy alien has become a pop culture icon, often used as a synechdoche representing video games as a whole.

Gameplay

The player-controlled laser cannon shoots the aliens as they descend to the bottom of the screen.
Space Invaders is a two-dimensional fixed shooter game in which the player controls a laser cannon by moving it horizontally across the bottom of the screen and firing at descending aliens. The aim is to defeat five rows of eleven aliens—some versions feature different numbers—that move horizontally back and forth across the screen as they advance towards the bottom of the screen. The player defeats an alien, and earns points, by shooting it with the laser cannon. As more aliens are defeated, the aliens' movement and the game's music both speed up. Defeating the aliens brings another wave that is more difficult, a loop which can continue indefinitely.
The aliens attempt to destroy the cannon by firing at it while they approach the bottom of the screen. If they reach the bottom, the alien invasion is successful and the game ends. A special "mystery ship" will occasionally move across the top of the screen and award bonus points if destroyed. The laser cannon is partially protected by several stationary defense bunkers—the number varies by version—that are gradually destroyed by projectiles from the aliens and player.

Development
Space Invaders was created by Tomohiro Nishikado, who spent a year designing the game and developing the necessary hardware to produce it. The game's inspiration is reported to have come from varying sources, including an adaptation of the mechanical game Space Monsters released by Taito in 1972, and a dream about Japanese school children who are waiting for Santa Claus and are attacked by invading aliens. However, Nishikado has cited Atari's arcade game Breakout as his inspiration. He aimed to create a shooting game that featured the same sense of achievement from completing stages and destroying targets, but with more complex graphics. Nishikado used a similar layout to that of Breakout, but altered the game mechanics. Rather than bounce a ball to attack static objects, players are given the ability to fire projectiles at their own discretion to attack moving enemies.
Early enemy designs included tanks, combat planes, and battleships. Nishikado, however, was not satisfied with the enemy movements; technical limitations made it difficult to simulate flying. Humans would have been easier to simulate, but Nishikado considered shooting them immoral. After seeing a magazine feature about Star Wars, he thought of using a space theme. Nishikado drew inspiration for the aliens from H. G. Wells' The War of the Worlds—he watched a film adaptation as a child—and created initial bitmap images after the octopus-like aliens. Other alien designs were modeled after squids and crabs. The game was originally titled Space Monsters, inspired by a popular song in Japan at the time ("Monster"), but was changed to Space Invaders by Nishikado's superiors.

Hardware
Because microcomputers in Japan were not powerful enough at the time to perform the complex tasks involved in designing and programming Space Invaders, Nishikado had to design his own custom hardware and development tools for the game. He created the arcade board using new microprocessors from the United States. The game uses an Intel 8080 central processing unit, and features raster graphics on a CRT monitor and monaural sound generated by analogue circuitry. Despite the specially developed hardware, Nishikado was unable to program the game as he wanted—the Control Program board was not powerful enough to display the graphics in color or move the enemies faster—and considered the development of the hardware the most difficult part of the whole process. While programming the game, Nishikado discovered that the processor was able to render the alien graphics faster the fewer are on screen. Rather than design the game to compensate for the speed increase, he decided to keep it as a challenging gameplay mechanic.
Space Invaders was first released in a cocktail-table format with black and white graphics, while the Western release by Midway was in an upright cabinet format. The upright cabinet uses strips of orange and green cellophane over the screen to simulate color graphics. The graphics are reflected onto a painted backdrop of a moon against a space background. Later Japanese releases also used colored cellophane. The cabinet artwork features large, humanoid monsters not present in the game. Nishikado attributes this to the artist basing the designs on the original title, Space Monsters, rather than referring to the in-game graphics.