The last Youtube video by JB le Daron is about an Amstrad CPC adventure game with graphics by Ubi Soft : Omeyad released in 1989.
The description given by JB le Daron and the test of the game on CPC Game Reviews should make you playing the game (well if you understand french of course). The story takes place in medieval Arabia in the city of Omeyad. You will have to meet several of people of the town who will give you missions to complete. Of course you will have to use objets to do that. The town and its people are reacting to what you do, which is rare in games!