Sierra Games Mysteriously Came Out of Nowhere and Dropped This Teaser

Sierra Entertainment, known for impossibly hard adventure games like King's Quest and Space Quest, and publishing games like Crash Bandicoot and Spyro, disappeared after being bought and merged with Activision many years ago. Then, last night, the company's website stopped redirecting to Activision and posted this teaser. Looks like we'll be seeing something from them at Gamescom, but what?