There should be a “Campaign” button to the right of the “Battle” button at the main screen. That will be your entry into the Galactic Conquest campaign, I believe.
From Steam’s Game Library, right-click on Gratuitous Space Battles and select “View Downloadable Content”. Galactic Conquest should appear there (along with any other DLC you’ve purchased for GSB through Steam). Any DLC you’ve purchased for GSB through Steam will install (and uninstall, should you so desire) with the core game, and when you purchase DLC I believe it will just trigger an update download to add the additional content (assuming you already had the core game installed) which may explain why the Install Game button did nothing.
So, the Galactic Conquest DLC is hidden under the campaign feature?
I haven’t played with that before. (if it existed before)
When I do, it says I should click on the Online button.
When I do that, it asks for a registration code.
I looked at my steam sale email notification and it doesn’t mention a registration code.
Where do I find this code?