Ground Zero Texas for the Sega CD. I was so excited to get it, but man is it terrible. And don't rag on me for anticipating an FMV game. I was young! And Tex Murphy had inspired me so much!
Oddly enough, I too picked up Back to the Future on a whim years ago. I blame R. Zemeckis for making such a great movie. Speaking of, Who Framed Roger Rabbit was also a game I looked forward to playing, but could never figure out what to do in it. Except punch Roger in the face.