Halo added jump boosts so you can jump higher than what a normal player can in a game like Call Of Duty. If you use this strategically you can potentially use the jump boosts to your advantage. Little things like this were added and have developed into things like perks that can assist you and make your game play better. Halo uses a controller layout that has been modified and changed slightly into a system that feels better when you play it. I think thats why Call Of Duty is so popular because it just feels right.