zarx on 16 February 2013
CD Key sites like that one usually obtain their bulk keys from Russian and Asian destributers. While not strictly illegal it is frowned apon and against the Steam (and others) TOS, and publishers try actively to block the practice sometimes blocking activation of such keys in other regions.
Many such sites have also been known to obtain keys by straight up illegal methods including defrauding smaller distributors, tho I am not sure if this site is one of the ones that has done that.
As a basic rule I personally avoid such sites, you are better off with legit services like GreenManGaming, Amazon etc than these shady sources.
@TheVoxelman on twitter
