From the original High Speed Halo News Post:
“The Halo 3 Zero Shots page goes live today. These unique runs are only different from regular runs in that you must not fire any ranged weapons. This usually means that you must find clever alternate methods to proceed through the Mission. For Halo 3 the strategies have greatly changed from Halo CE (boarding vehicles, exchanging weapons etc.) and from Halo 2 (equipment, smarter AI etc.) and you now have the Arbiter to help you along the way.
The first two runs are very good examples of the new techniques Halo 3 offers. XBmaster strolls through Floodgate, in 4:22, as if he were invisible. Proving that sometimes it is best not to shoot and attract enemies. LegacyXI demonstrates that The Storm is a Mission taylor-made for a Zero Shot run with his 19:35 romp through the warehouse district. It’s almost as if Bungie watched all the Halo CE and Halo 2 Zero Shots and decided to gift us with the perfect Zero Shot Mission. Yes, there are still challenges, but the first two thirds can be spent driving gunners from enemy to enemy. Thank you Bungie.“