I have played several of the Adventure Company games you mentioned Heimdall. Some were fun, some awful I loved Voyage, my granddaughter and I are playing Barrow Hill right now. Not as high tech as Myst. And nanoukmetal, I tried Schizm and it is indeed extremely challanging. I had just gotten past a very frustrating puzzle when my laptop motherboard got fried and I lost my saved games. I have looked at that disk a few times but couldn't bring myself to pick it up again. Maybe someday... I played Zork a long time ago and loved it, maybe it is time to play it again. I never heard of Crystal Key 2. I will look into the others you both mentioned.
Hopefully by tomorrow I will be able to leave my air conditioned bedroom in the evening after work to use the computer room - it is 90 degrees in my house tonight and I can't bear to leave this cool room. I live in western NY state and we have had several scorching hot days with high humidity.
Thanks!