The Amstrad CPC version of Martianoids is arguably slightly better than the ZX Spectrum version, because it has a couple more on-screen colours to play around with. It plays the same as the Spectrum version, but looks a little better. The scrolling and control responsiveness seem a little slower, though.
The gameplay revolves around a robot that is protecting nine different sectors of a large computer from alien attack. The robot can move around a scrolling landscape by rotating and moving forward and can fire a blaster for destroying enemies, or a laser for destroying walls (although it doesn’t look like a laser, more like a ball of plasma). The aim of the game is to a guide a program from the transmitter to the receiver in each sector. When the program is received the internal defences are activated, thus preventing further damage in that sector.
How to actually do the above, though, is beyond me. I spent a day playing all three versions of Martianoids (this, ZX Spectrum, and MSX); I read the instructions; referred to a map, and I tried everything I could to ‘guide’ the program to the receiver, but only managed to complete the process once. By accident.
So walking around, blasting alien robots, wears very thin quickly. Martianoids is another failed US Gold/Ultimate game which has objectives that are not explained properly, and shallow, repetitive gameplay.
More: Martianoids on Wikipedia