A beta version of Sentinel 3: Homeworld is now available to all game owners. This update adds the Campaign 2 expansion pack to the game, plus Steamworks support and achievements.
To access the beta, right-click on Sentinel 3 in your Steam Library, select Properties, click the "Betas" tab, then opt in to beta. The update should start downloading immediately.
Please report any problems with the update in the forum, and enjoy the new content!