Galaga | Code Like It's 198x

In Galaga the enemy can take your ship. Every so often a Boss Galaga drops out of the formation, hovers above the player and spreads a tractor beam down the screen. Get caught and the fighter tumbles up into the beam and is carried back to the formation as a prisoner, at the cost of a life. Shoot the Boss while it dives, though, and the captured fighter comes back down and locks on beside the new one: two ships, moving together and firing together. Namco released it in September 1981 as the sequel to Galaxian, and Wireframe has called that rescue “one of the first – if not the first – power-ups in a shooting game”.

Fast facts

Developer: Namco; in arcades in September 1981.
Designer: Shigeru Yokoyama.
Predecessor: Galaxian (1979).
American licensee: Midway.
Hardware: three Z80 processors sharing memory, with Namco custom chips for the starfield, the explosion sound and input.
Home versions include: Sega’s SG-1000, Namco’s own versions for the Famicom and MSX, the NES, the Atari 7800 and the Game Boy.

From Galaxian to Galaga

Namco asked Yokoyama for another fixed-screen shooter “in the Galaxian vein”, Ryan Lambie writes in Wireframe, and he designed it in about eight weeks. Looking at Galaxian’s diving aliens, he thought: “Rather than just firing bullets at the player, what if the enemies could use a tractor beam to suck up their ship?” He later said the beam came from a science-fiction film whose name he could no longer remember. His first plan was that a rescued ship would simply be an extra life, until he saw that this was not much different from earning one by scoring points. The double ship was the answer.

It came with a catch. Two ships meant twice the firepower and twice the target, and a careless player could shoot the captured fighter instead of the alien holding it. JoyStik’s 1983 guide warned that a captured fighter shot down was worth 1,000 points, “but it is much more valuable if you can free it”. Some players let a Boss take their ship on purpose, trading a life for the chance of a double ship.

Playing it

The aliens do not start in formation: they fly in from the top and sides in lines, loop around the screen and settle at the top, and only then start peeling off to attack. The entry patterns are always the same for a given stage, which made memory as important as reflexes. In 1985 Julian Rignall, who had won Computer and Video Games’ 1983 arcade championship, explained how to play it for the magazine. There were three kinds of alien, he wrote: blue ones that loop back at the bottom of the screen, red ones that “swerve crazily down the screen straight past you”, both worth twice as much in the air as in formation, and the Boss Galagas, worth 400, 800 or 1,600 points when diving “depending on the size of escort”. A Boss takes two hits, turning blue after the first.

From the fourth stage on, a red or blue alien may flash and split into three, heralded by a sound; destroying all three is worth a bonus of up to 3,000 points. After the second stage and on every fourth stage after that comes a Challenging Stage. Forty aliens fly in, in five groups of eight, and they neither shoot nor bomb. Each hit scores 100 points, and hitting all 40 earns a 10,000-point bonus. Retro Gamer counts the Challenging Stages among Galaga’s “pioneering features”, an idea “subsequently stolen by countless games”.

Retro Gamer notes that the player’s ship gained “the ability to shoot multiple times in quick succession”, and that rapid fire was “most definitely required”. JoyStik thought Galaga “may be the only shooting game in which you rarely need to aim”, because a player who knows where each wave will arrive can wait for it.

Inside the cabinet

Galaga runs on the same kind of board as Namco’s Bosconian: three Z80 processors sharing memory. MAME’s notes from the schematics describe custom Namco chips alongside them, among them a starfield generator (05XX), an explosion sound generator (54XX) and an input chip (51XX). The reverse-engineering site Computer Archeology, which has disassembled the program, describes the work split: one Z80 runs the game, a second moves the aliens and their shots, and a third plays the sound.

That split explains the game’s best-known flaw. Arcade players found that if they cleared the first stage except for one or two of the bees in the left-hand columns and then dodged their fire for a long time, the aliens eventually stopped shooting for the rest of the game. JoyStik printed the trick in October 1983: wait “anywhere from about five to 20 minutes — we don’t know why it isn’t always the same”, and once the survivor has passed through the top of the screen four times without firing, “none of the bugs will fire at you”. Computer Archeology’s disassembly found the reason. The game keeps a fixed set of slots for the aliens’ shots and marks an unused one with a horizontal position of 0. A shot fired while an alien is at position 0, which happens most often to aliens diving from the edges of the formation, is never moved and never cleared. Each one permanently fills a slot, and when every slot is full, no alien can fire.

Midway and the arcades

Midway, which already built Space Invaders and Galaxian under licence, took Galaga for America. MAME holds several Midway sets marked “Namco (Midway license)”. Retro Gamer found one difference in them: operators could set a switch so that an extra credit bought a single-player game with more ships, usually seven instead of three, a feature Midway also tried on Wizard of Wor, Solar Fox and Omega Race (see difficulty design).

The game was a hit. Electronic Games listed Galaga (Midway) fourth among the most popular coin-ops in February 1983, and JoyStik wrote that October that it had been “one of the ten most-played games in the country for over a year”. In Britain, Julian Rignall’s prize for winning Computer and Video Games’ 1983 championship was a Galaga machine.

At home

Sega made a version for its SG-1000 console. Sega-Galaga was, in Retro Gamer’s words, “pared down to the bone”: no Challenging Stages and no splitting aliens, and a formation so large that it attacked “in large numbers almost from the off”. Namco published its own version for the Famicom in 1985, and Edge named Galaga among Namco’s “first big Famicom sellers”. Namco’s home label, Namcot, also sold it on MSX cartridge. Nintendo Power previewed the American NES version in September 1988, promising players could “relive arcade memories” with a Challenging Stage “every third assault” and a hit-ratio count at the end.

Atari’s 7800 cartridge sold for $19.95. Reviewing it for ANALOG Computing in June 1988, Joyce Worley described aliens that “twist and turn like living things, making them devilishly hard to hit”, and decided that “Galaga for the home lives up to its coin-op antecedents”. A Game Boy cartridge pairing Galaga with Galaxian went straight into Nintendo Power’s Game Boy chart in September 1995.

Sequels and revivals

Namco carried the idea on. Gaplus followed, and Galaga ’88, released in December 1987, added short scrolling sections between waves and, as Zzap!64 described it, a “giant” ship for a player who rescued a fighter while already flying a double ship. Wireframe noted the cost: capturing a ship a second time made the player’s craft “even larger and more vulnerable to attack”.

The original stayed in print. Edge reviewed Namco Museum Vol. 1 for the PlayStation in February 1996 and called Galaga “an incredibly tough and addictive blast”. Namco also used it as a loading screen: the PlayStation Tekken let players shoot their way through three stages of Galaga while the fighting game loaded, and Edge called it “arcade-perfect”. By 2006 it was on sale again on the Xbox 360’s download service.

Sources

Wireframe issue 39, May 2020, pp. 112–113, Ryan Lambie, “Killer Feature: Galaga”: Yokoyama, the eight weeks, the tractor beam and its origin, the extra-life idea, the double ship, “one of the first – if not the first – power-ups”, Galaga ’88.
Edge issue 8, May 1994, pp. 54–61: Namco feature and game history (Galaga, September 1981; Galaga ’88, December 1987; Namco’s first big Famicom sellers).
Retro Gamer issue 116, July 2013, pp. 14–15: September 1981 (Galaga in arcades; Midway’s American distribution; faster fire; Challenging Stages).
Retro Gamer issue 32, 2006, pp. 69–75: the Galaxian series (Galaga’s Challenging Stages, Midway’s extra-ships switch, Sega-Galaga, Gaplus, Galaga ’88, the Xbox 360 version).
Computer and Video Games issue 43, May 1985, p. 95, Julian Rignall, “Get to grips with Galaga”: the aliens, scoring, splitting aliens and the Challenging Stages.
JoyStik special edition, October 1983: Galaga strategy guide (entry patterns, the Boss and the double ship, “one of the ten most-played games in the country for over a year”) and pp. 60–61, the trick that stops the aliens firing.
Electronic Games vol. 1 no. 12, February 1983: “Most Popular Coin-Op Videogames” chart.
ANALOG Computing issue 61, June 1988: Joyce Worley’s review of Galaga for the Atari 7800 ($19.95).
Nintendo Power issue 2, September 1988, p. 82: “Pak Watch”, Galaga for the NES.
Nintendo Power issue 76, September 1995: Galaga/Galaxian for the Game Boy, new in the Game Boy chart.
MSX Computer Magazine (Netherlands) issue 40, September 1990: mail-order listing of Galaga (Namcot) for MSX.
Zzap!64 issue 35, March 1988: Galaga ’88 (arcade), the scrolling sections and the larger ship.
Edge issue 21, June 1995: Tekken review (PlayStation; Galaga during loading).
Edge issue 29, February 1996: Namco Museum Vol. 1 review (PlayStation).
MAME source code, src/mame/namco/galaga.cpp: the three-Z80 board, the custom chips, and the Namco and Midway sets. https://github.com/mamedev/mame
Computer Archeology, “Galaga” (web, secondary): disassembly of the arcade program, the work of the three processors, and the cause of the “no fire” bug. https://www.computerarcheology.com/Arcade/Galaga/
Jason Eckert, “The Galaga no fire cheat mystery”, 31 October 2012 (web, secondary): the trick and its explanation. https://jasoneckert.github.io/myblog/the-galaga-no-fire-cheat-mystery/