Halo Tips

Run Through A Locked Door
With co-op, yes, you can run through a door. On "the silent cartographer" kill all of the enemies in the small pit where they lock the doors. After the aliens are dead, have one person (with a pistol) stand next to the locked door. Have that person aim and zoom in at the door. Have the other person drive a warthog straight at the door. Normally the person would die, but they will go straight through the door.

PLEASE NOTE: The person in the warthog will not go through the door, so this might be a good thing to do if you control both people.