If you have been playing the Dark Souls Prepare to Die Edition you will want to know about the latest update that changes some things in the game. The most important part is the replacement of Games for Windows Live functionality with Steamworks functionality.
The official Steam website received a post from the developers couple of hours ago where they have announced the news and shared detailed instructions regarding the process of the update:
If you played or are currently playing Dark Souls Prepare To Die Edition, you will be able to update and keep your Save Data and Achievements. The Save Data and Achievements transfer service is being provided from December 15th to February 16th. From February 16th, the new version using Steamworks functionalities will become the default version of the game.
The update went live on December 15, 2014 i.e. yesterday and thankfully, it will not affect your Save Data and Achievements if you convert now.
However, the developers have warned that they will not be responsible for the Save Data and Achievements after February 16, 2015. That is when the Steamworks functionality will completely take over.
They have listed down multiple cases for you to update the game. There’s a separate set of instructions for you if you purchased the Dark Souls Prepare to Die Edition before December 15, and in them, for those who purchased the Game for Window live from Steam or from retailers.
Then there is also a separate process for anyone who purchases the Dark Souls Prepare to Die Edition after December 15 but before February 16. Everyone purchasing it after February 16 will not need to do anything, of course, as the Steamworks functionality will be already in place.