First and foremost weaponry, it's probably been covered a lot but things like mounted guns, I don't think are necessary. (We do already have pikes) instead, how about the ability to draw your weapon on the go? Switching weapons with a tap of a button while boosting past enemies. More diverse appearance options would also be a welcome addition, or set events like sparrow races to add spice to the larger areas of the game. Feel free to add ideas people, let's hope Bungie adds some of them! (Hand cannon headshots from your sparrow though -.-)