Alien Syndrome was originally released in 1987 for the arcades and ported a year later to the Sega Master System, MSX, Amiga, Atari ST, Amstrad CPC, Commodore 64, and Famicom/Nintendo Entertainment System (published by Tengen). It was so popular that ported later on the ZX Spectrum (1989) Sega Game Gear (1992) and Sharp X68000 (1992), the latter being the only arcade perfect port.
The game features single and two-player game-play in a top-view eight-way scrolling maze. Ricky and Mary must fight their way through large eight-way scrolling levels rescuing their fellow comrades who are being held by aliens (mutant sausages and jellies!). By rescuing a certain number of hostages the exit opens and they can proceed to the next stage. Note that at the end of each stage there is a guardian who's going to make you a hard time! There are several stuff to pick-up in each stage including better weapons and maps of the current level. But the mutant sausage and jelly aliens will always shoot at you from close distance and that's makes the gameplay rather difficult. So just a quick hint here: don't run always to the edge of the gameplay screen. Wait for the screen to scroll first in order to have visibility of what is coming!
The CPC version offers nice graphics, featuring nicely drawn stages running in Mode 1 (320x200 pixels with 4 colors) and generally resembling as much as possible the original (arcades) details. Sprite animation though is poor and the overall action is slow. Technically the C64 is the best among the other 8bit conversions in terms of playable area size and faster action. The CPC port features a rather repetitive kind of tune during gameplay music along with a few typical SFX. Soundwise it cannot compare to the way superior C64 version.
CPU: ZiLOG Z80 4MHZ MEMORY: 64 KB or 128 KB of RAM depending on the model (capable of being expanded to 512k using memory extension boards) GRAPHICS: Motorola 6845 address generator, Mode 0: 160x200 / 16 colors, Mode 1: 320x200 / 4 colors, Mode 2: 640x200 / 2 colors, A colour palette of 27 colors was supported SOUND: The CPC used the General Instrument AY-3-8912 sound chip, providing 3 channels Mono Sound (via internal speaker) but capable to offer Stereo Sound provided through a 3.5 mm headphones jack (with pretty impressive outcome!). Also, it is possible to play back digital sound samples at a resolution of approximately 5bit. This technique is very processor-intensive though.