THE LIBRARY

HALO>SINGLE PLAYER>LEVEL WALKTHROUGH>THE LIBRARY

Ideal arsenal: Shotgun and assault rifle.
Best tip: Use the Exploders to help you.
hardest part: Getting to the index.
How to beat it: Forget about defeating every enemy. Make a run for the goal.
Cool thing to try: Use precision firing to knock the limbs off your enemies.

WALKTHROUGH

This is another straightforward, but difficult level. Below are some tips to help you:

Keep moving: stay away from Exploders.

Use the shotgun for big enemies and assault rifle for small ones.

If you find a rocket laucher, use it quickly and pick up your main gun.

Shoot the Exploders when they're close to other enemies.

Use every grenade. you'll get plenty more.

When the game finally tells you to recover the index... go straight for it. There are just too many enemies, and is you have a full life you should be able to make it pretty easily.