Um...I'm fairly sure everyone thought of it, and then realized "oh right, it
was a book first, not a video game, so it doesn't count".
Well, everyone except one person, apparently.
Shinarae Lluminus
Hmm... You'd spotted the humour if you'd seen this norwegian tv-commercial
where som guy says sighingly "Duh, now they've made LOTR into books as well"
or something...