Its amazing what microsoft has done to bungie. In the marathon games they encouraged people to mod releasing the tools to use to make entire new games. They even made simple versions that normal people could use without much trouble (changing projectiles that fire out of guns) but, included more complex tasks importing graphics, textures, making maps (yes not only multiplayer maps but, entire multi level senarios), and complete control of the in game physics system (everything from bullet speed and damage to alien strength and speed to ally and enemies and much more). Why do they look down on modding now. I blame microsoft.