Recently bought Earth2160 but for some reason I cant activate the game it wont let me do anything but play the ED Campaign, can anyone let me know what the fix is there. I have already e-mailed Support Staff for GOG. I am hoping that this might bring the problem to GOG Staffers attention they can start sending out activation codes with the game.
On singleplayer when you start a new game, only the ED and LC campaigns are available. Finishing these will unlock the others.
If you mean activation for Lan/Multiplayer, all you have to do is send an email to support asking for your key and you'll get one.
You don't need a serial or activation for singleplayer.
Check out this support article