[Endoperez]

If it had the manual, it's probably fine, but it's hard to be sure... Shrapnel Games sells the game without a box, with the cd shrinkwrapped inside the manual for 50$.

If your cd-key is on the first page of a 300-page ring-bound manual, at worst it's a used game and someone else is using the same key, which should only matter if you happen to play against him. I don't believe anyone would go to the trouble of reprinting the manual to go with a pirated copy.