In the images below you can see a message received which contained the code, along with the next image offering the download of the game. It appears this is only for Episode 1, however, meaning you’ll need to purchase the other episodes to get the full experience. But, free is still free, so it’s nothing to complain about.
Images are from Total Xbox.
It’s unsure how you end up becoming a ‘valued’ member. I went and checked my Xbox 360 for a message but, alas, there was nothing to be found. I’ve been subscribed for over seven years, so it’s doubtful they’re using that to define ‘valued’. Perhaps it’s to do with purchases? Who knows. Anyway, please let us know if you’ve received one of these messages, it would be interesting to know how common or rare they are.