The Graphic Adventure Creator
The Graphic Adventure Creator (often shortened to GAC) was a game creation system/programming language for adventure games published by Incentive Software.
Its main advance over the already well established The Quill was a clever graphics editor, one of very few vector graphics editors for the CPC.
This enabled pictures to be drawn using a minimal amount of memory.
In the heyday of the CPC, few major-label commercial games were produced using GAC (probably fewer than with The Quill), but it had a vast following in the homebrew and public domain scenes - despite a comparatively high retail price of £24.95 in the UK.
Amstrad Action launched a competition to produce an adventure and have it featured on a later covertape.
The covertape didn't include two standalone adventures which accompanied GAC in it's original package when released.