This summary is directly from http://7daystodie.com/alpha-15-release-notes/. Please click the link to view more!
"Hey Survivalists,
Here are the release notes for the upcoming Alpha 15 release. We know you folks like to read them beforehand so we’re releasing it early. If you’d like to participate in testing an early experimental version, please go to our forums news and announcements to learn how.
This update has some big framework changes so starting a new game is a must. Please don’t try to salvage your old saved game. And for those of you that experience any problems please use your steam client to delete local files and reinstall the game. Also wiping your player profile data might be helpful.
Credited to the Fun Pimps LLC, http://7daystodie.com/alpha-15-release-notes/