Three Weapons in the pillar of autumn
Once you get to the captain, run out of the bridge before the chapter name disappear's, if you were fast enough, the checkpoint wouldn't have triggered. Now go get your assault rifle in the mess hall and run back and trigger the checkpoint. Now go back to the mess hall and there will be two pistols and one AR in your hands. NOTE: This will only last for the first level.
The Lone Marine (You will need a Dev (Development) trainer on or this will not work)
In the sixth level (343 Guilty Spark) open your dev trainer, and turn on deathless player (or you will die while falling) and super jump. Keep walking until you find a covenant dropship (do not go into the structure) jump on top of the ship, and then on the cliff. Walk east until you find a marine, you may kill him if you like.
The Talking Grunt
In the last level, there will be a tunnel with a corridor to the right that will be open. Walk into the corridor and there will be another corridor to the right, go into that one. There will be a grunt that will not shoot you, walk up to him and see what he has to say.
How to make a flood juggernaut to be your companion
If you have a shotgun and a happy trigger finger, this will work. Take a shotgun and walk up to a juggernaut, if you shoot him just right he will not die, but help you fight.
