Gryzor was a port from the Arcade game Contra from Konami. (Also known as Probotector on Nintendo Entertainment system)
The Home Computer's ports (Amstrad CPC port too) were mostly produced by the Famous amongst Amstrad CPC user OCEAN company from England.
Gryzor is probably one of the best game available on Amstrad CPC, and is probably featured in every Top10 games for this standard.
This is a "Run and Gun" style game, such as games like : Robocop, Midnight resistance...
With vertical, horizontal and 3d (sort of) action.
It is well known for :
--Awesome colorfoul graphics.
--Nice Music.
--excellent playability and fast action.
--various levels and gameplays.
Despite this, this game is not flawless :
--lack of smooth scrolling.
--lack of a proper 2 player mode.
This is probably the best port amongst 8 bit computers, always refered as by Amstrad CPC fans in the "8 bit war" when C64 users claim it as a lame machine.
Even the MSX or [Commodore 64|C64]] ports where Failed compared to the sweet CPC version.