I purchased Myst Revelations last year but never could play it due to only one half screen showing the game. It was like the game is cut in half. I tried adjusting screen resolution but that didn't do anything. I asked Apple and they told me to ask the creator of the game. Myst Masterpiece and Riven work perfectly. It is the same for Myst games after Revelations also. Mine is an iMac late 2014 i5 27" (stock but for upgraded RAM). I bought the games from Steam and GOG as downloads. No answers from them either so I thought I would ask if there was a solution here. When you have the time, please get back to me.