10. The Legend Of Zelda: Ocarina Of Time
Ocarina of Time, first released by Nintendo in November 1998 for the Nintendo 64, is a classic RPG. It won Game of the Year in 1999 at the 2nd Annual Interactive Achievement Awards, among other honors. It has been rereleased for other consoles, and was such a success that a direct sequel, Majora's Mask, was released a mere 18 months later.
Why it would make a terrible film: The main character, Link, travels back and forth through time, between when he is a child and an adult, in order to fulfill his role as Hero of Time. Half the time the character is prepubescent, and half the time he is fully mature, and that might not go over well with a film audience. In our hyper-sexualized society, films tend to insinuate sexual tension between characters, and also tend to reward the hero with a beautiful woman. Cue Princess Zelda who, despite not hooking up with an adult Link at the end of the game, makes the perfect prize. But any sexual or romantic tension between the two will feel awkward, forced, and possibly dirty. Link sleeps while his body transitions from child to adult, so just how adult can his mind actually be - especially when he continuously goes back and forth? That being said, an animated film could possibly be successful if devoid of romance and marketed with children in mind, but that would alienate much of the adult population who can actually appreciate the attempted adaptation.