Many Steam and Ubisoft customers are complaining that Heroes of Might & Magic 6 has become unplayable since the release of its recent expansion, Shades of Darkness, and the 2.1 patch that accompanied it. The issue seems to center around Ubisoft's Uplay service, which refuses to accept the download codes issued to customers after they buy the game.
Users are saying that the problem arises after downloading the game and activating their key within Uplay. Upon booting the game, the in-game store page asks for the same key. If the key is entered again, the game produces an error message that the key has already been redeemed. After this, players have access to the Heroes 6 expansions, but are unable to play the main campaign (it's grayed out in the menu).
For its part, Ubisoft has acknowledged the issue on its own forums, assuring users that their keys are "not broken and will be fixed as soon as possible." The company is also recommending a workaround discovered by forum user ElektroDragon, which involves manually downloading and installing the patch instead of allowing the game to do it automatically.
Meanwhile, Steam users have started a petition against Ubisoft, specifically its use of 3rd party DRM via Uplay. The publisher has a rocky history with its PC games, often releasing them long after their console counterparts and saddling them with restrictive DRM. Earlier this year, Ubisoft's Uplay director, Stephanie Perotti, said that the company is working to improve its relationship with the PC community.
We've contacted Ubisoft regarding this latest issue and will update this story if we hear anything new.
Update: The specifics of the problem have been clarified. Thanks to commenter LamiaMistral for providing the image above.