User blog comment:Damac1214/Call of Duty: Advanced Warfare is Built on a New Engine, Says Sledgehammer/@comment-180.191.43.95-20140514052201

And by new they mean the old engine with new attachments. Seriously. That engine is on life support now. They wouldn't dare change the engine, why? Because that would drastically change how the game handles and hardcore COD fans won't get the COD "feel" they are used to. They would therefore lose a lot of audience.