Xecutor is at the start a shoot them up on ZX Spectrum by Cybadyne in 1987. Today Enrique G. Gálvez has ported Xecutor on Amstrad PCW (available on PCWWiki. You can play it solo or with a friend, it supports joystick with the hardware expansion DK'Sound (by DK'Tronics) and as usual colour support with the CP/M Box emulator by HabiSoft.