They seem to bring back stuff from past Halo games( namely a few characters and weapons) but what ever happen to the Brutes and the war hammer? I loved using that over the energy sword. And it would be cool to play as a Brute.
Or you know… the flood
Right now we have covenant and glowy harder covenant with no real tactic change needed between the two at least the flood you needed to mix up your play style and it felt like you were fighting something different.
i miss the brutes and the brute shot 
I really want the flood back in the next game. Along with both the brutes and the engineers. What happened to those things?