A few days ago Amstrad CPC World did post a video about an Amstrad CPC game in 3D isometric : Sepulcri, which I didnt know. Then I found on his channel a compilation of many 3D isometric games for Amstrad CPC (January 2019), a lot of them that I never knew !

P.S. : graphics in Sepulcri are done by Jill Lawson, use the link to the what she did, it's beautiful.