CVG, BioWare gameplay designers Christina Norman and Corey Gaspur detailed some of the changes that have been made to the Mass Effect combat formula for Mass Effect 3. According to Norman, BioWare wanted to shift the focus of combat, making it more about positioning than simply shooting and using abilities.
To help complement this idea, enemies were designed with better AI to work as a coordinated force, with certain units designed for specific roles. Norman likened the concept to a chessboard, where each piece can work together, but different pieces will interact with one another in different ways. All of these factors, according to Norman, lead to a more challenging game. "It's not just that the game is harder on Insanity," said Norman, "it's that this creature actually behaves differently on higher difficulty levels."
Just remember, bad guys: Singularities don't care how smart you are.