Unread postby klaymen » 20 Nov 2011, 12:39
As far as I know, Heroes 6 doesn't use Steamworks, therefore you cannot activate the key there.
Only Valve's own games and those which use Steamworks (Dawn of War 2, Modern Warfare 2, etc.) can be activated on Steam, with a few more exceptions - like Dark Messiah uses Steam for multiplayer and singleplayer does not. You can register your key on Steam to get access to both sp and mp, though if you don't want to play mp at all, you don't need to do it.
"The only good is knowledge and the only evil is ignorance."
-Ahzek Ahriman