Ajax, known as A-JAX in Japan, is a vertically scrolling shoot 'em up

Shoot 'em up

Shoot 'em up is a subgenre of shooter video games. In a shoot 'em up, the player controls a lone character, often in a spacecraft or aircraft, shooting large numbers of enemies while dodging their attacks. The genre in turn encompasses various types or subgenres and critics differ on exactly what...

 arcade game

Arcade game

An arcade game is a coin-operated entertainment machine, usually installed in public businesses such as restaurants, bars, and amusement arcades. Most arcade games are video games, pinball machines, electro-mechanical games, redemption games, and merchandisers...

 released by Konami

Konami

is a Japanese leading developer and publisher of numerous popular and strong-selling toys, trading cards, anime, tokusatsu, slot machines, arcade cabinets and video games...

 in 1987

1987 in video gaming

-Notable releases:* January 14, Nintendo releases Zelda II: The Adventure of Link in January for the Famicom Disk System in Japan only. The game would go unreleased in America for nearly two years afterwards.* February 20, Konami releases Contra...

. The game was also released on the home computer

Home computer

Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...

 systems ZX Spectrum

ZX Spectrum

The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...

, Amstrad CPC

Amstrad CPC

The Amstrad CPC is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the Sinclair ZX Spectrum, where it successfully established itself primarily in the United Kingdom,...

 and Commodore 64

Commodore 64

The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

 in 1988 by Imagine Software

Imagine Software

Imagine Software was a British video games developer based in Liverpool which existed briefly in the early 1980s, initially producing software for the ZX Spectrum and VIC-20...

 under the name Typhoon, the one chosen for distribution outside Japan and on Sharp X68000 by SPS as "A-JAX" in its home country. The players control a "Tom Tiger" helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 (in the 2D

2D computer graphics

2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models and by techniques specific to them...

 stage) and later a "Jerry Mouse" fighter jet (in the 3D

3D computer graphics

3D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images...

 stage), and shoot enemies in the air and bomb them on the ground, collecting power-up

Power-up

In computer and video games, power-ups are objects that instantly benefit or add extra abilities to the game character as a game mechanic. This is in contrast to an item, which may or may not have a benefit and can be used at a time chosen by the player...

s and defeating bosses

Boss (video games)

A boss is an enemy-based challenge which is found in video games. A fight with a boss character is commonly referred to as a boss battle or boss fight...

 to advance levels.

Gameplay

The game takes place in a fictional 2007 where the Earth has been conquered by alien invaders. The player combats the occupation forces using vehicles under operation code named 'A-Jax' created to liberate the Earth. Game play is divided into two scrolling sections with two different vehicles: the first being a vertical scrolling section with the helicopter and a Rail scrolling stage with the jet/space fighter. The game spans eight stages and extends are set to 30,000 and a second at 150,000 points.
During the helicopter segments, the player has access to four different weapons including the Vulcan, Bomb, 3-Way, Triple and Laser. Each weapon is available through their own specific pick-up icon. However, the helicopter can only equip one firing weapon at a time with the Bomb being constant. The player also has access to Options which add additional firepower. The jet segments contrast highly from the helicopter segments in the complete lack of available power-ups and additional weapons beyond a machine gun and bomb.

Ports

The IBM PC

IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

 and Tandy 1000

Tandy 1000

The Tandy 1000 was the first in a line of more-or-less IBM PC compatible home computer systems produced by the Tandy Corporation for sale in its Radio Shack chain of stores.-Overview:...

 ports were done by Banana Development, Inc. (Programmer - Logan Poelman, Artwork - Chris Grow and Brenda Johnson, Music - Kris Krug) It was written completely in 8086 assembly language

Assembly language

An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...

. A custom multitasking kernel was developed for the game, to provide for simultaneous animation, music, collision detection and scoring on the single tasking MS DOS operating system, quite advanced for the time on the IBM PC

IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

 platform. To support flicker free scrolling, double buffering

Double buffering

In computer science, multiple buffering is the use of more than one buffer to hold a block of data, so that a "reader" will see a complete version of the data, rather than a partially-updated version of the data being created by a "writer"...

 was used. The music routines supported 4 note polyphony on suitable sound hardware, as well as sound effects related to the game play. (The computer graphics and the music for the game were authored/transcribed on an Amiga 500

Amiga 500

The Amiga 500 - also known as the A500 - was the first “low-end” Commodore Amiga 16/32-bit multimedia home/personal computer. It was announced at the winter Consumer Electronics Show in January 1987 - at the same time as the high-end Amiga 2000 - and competed directly against the Atari 520ST...

and then the files transferred to the IBM platform used by the software designer.)