When you launch the game from the 'Play' button in Steam, you should see the following.
On the Stardock Account registration window that comes up, it should say 'GC2 Ultimate Edition', just like is highlighted with the red box.
If it says anything other than that, (Twilight of the Arnor) please do the following:
- Navigate to where the game is installed (by default C:\Program Files\Steam\steamapps\common\Galactic Civilizations II - Ultimate Edition)
- Run GC2Launch.exe
- Click 'Play the Game'
You should then see the window from the screenshot above. Enter in your account information and serial number and then click 'Register'. If you get an error or it does not show GC2 Ultimate Edition in the activation dialog like the image above, try running one of the other executables (GalCiv2.exe, GC2DarkAvatar.exe within the DarkAvatar folder, GC2TwilightOfTheArnor.exe within the Twilight folder).
If it still does not come up correctly, try right clicking on the executable and select 'Run as administrator'.
Once this has been done, it will activate the base game and all of the expansions and you should not see the registration dialog again.
**** If this does not resolve the issue, please contact support: Submit a ticket ****