Update: It seems to be for a instant download item you’d get, and not the demo. Flu: gotta love it.
Thanks, Slashgamer and DeforMAKulizer.
According to folk on GAF, the code doesn’t seem to be unique, which means anyone can download the demo if they knew the code.
We just tried it there on the special website for the demo, but it doesn’t seem to be fully active until tomorrow, when the game releases in the US.
Find more through the links.