From this teaser trailer it looks like Activision is dusting off the old Sierra brand that it's owned but hasn't used in years.
For old school PC gamers the Sierra name conjures up some great memories. For those who weren't around then the company was responsible for some great adventure franchises like Kings Quest (which was one of the first point and click adventure games), Leisure Suit Larry, Space Quest, and Police Quest. I'm not sure how many of those franchises the company still owns but we'll get more information next week at Gamescomm.
Stick tap to Polygon for the link.