Changes

When you enter the third room (not counting the elevator room) you normally turn right and go through a door. Instead, turn left, throw a plasma grenade at the base of the purple crates, then quickly hop on top of them and jump at the ledge above. The grenade should propel you up onto the ledge. Proceed forward through the door in front of you and you will be at the flood room early.

When you enter the third room (not counting the elevator room) you normally turn right and go through a door. Instead, turn left, throw a plasma grenade at the base of the purple crates, then quickly hop on top of them and jump at the ledge above. The grenade should propel you up onto the ledge. Proceed forward through the door in front of you and you will be at the flood room early.

=== The Library ==-

=== The Library ===

'''Sneaking through doors early'''

'''Sneaking through doors early'''

Throughout the Library, there are a number of large doors that the player often has to wait in front of as the monitor goes and opens it. Some of these doors, however, are opened a bit, revealing a small gap in the center of the door. Normally you can't get up to the hole, but with a bit of trickery it is possible. If in co-op mode, have one player stand next to the door, then the other guy hops on his head then up to the space in the door. If in single player, toss a grenade at the base of the door and jump off of it onto the edge of the door and hop through the gap.

Throughout the Library, there are a number of large doors that the player often has to wait in front of as the monitor goes and opens it. Some of these doors, however, are opened a bit, revealing a small gap in the center of the door. Normally you can't get up to the hole, but with a bit of trickery it is possible. If in co-op mode, have one player stand next to the door, then the other guy hops on his head then up to the space in the door. If in single player, toss a grenade at the base of the door and jump off of it onto the edge of the door and hop through the gap.

==Two Betrayals ==

===Two Betrayals ===

After you trigger the second beam, you go down into a tunnel and eventually encounter a large door that breaks and leaves a space too small for a banshee, and too small for a ghost to simply drive through. You can get a ghost through here in a decent amount of time. To do this, hop out of your banshee at the bottom of the large downward-sloping cavern grab the ghost there, proceed to the door ahead and hit the switch. Now back the ghost's tail into the door as far as it will go. Now toss a plasma grenade on one of the wings of the ghost so it starts to flip, and when the ghost is almost completely vertical, fire a rocket at it and it should pass through the door. Click here to see a short movie if this. Note: After taking the ghost through the door, many load points are a bit wonky, so you may have to slow down and wait for them or else critical things might not load, most notably the banshee needed for the final beam.

After you trigger the second beam, you go down into a tunnel and eventually encounter a large door that breaks and leaves a space too small for a banshee, and too small for a ghost to simply drive through. You can get a ghost through here in a decent amount of time. To do this, hop out of your banshee at the bottom of the large downward-sloping cavern grab the ghost there, proceed to the door ahead and hit the switch. Now back the ghost's tail into the door as far as it will go. Now toss a plasma grenade on one of the wings of the ghost so it starts to flip, and when the ghost is almost completely vertical, fire a rocket at it and it should pass through the door. Click here to see a short movie if this. Note: After taking the ghost through the door, many load points are a bit wonky, so you may have to slow down and wait for them or else critical things might not load, most notably the banshee needed for the final beam.

==Keyes ==

===Keyes ===

As you may or may not know, while an overshield is charging up (right after you first pick it up), you are completely invincible. This exploit can be used to quickly jump up to the gravity lift at the end of the below-the-ship part of the level instead of running all the way back around it. As you approach the area with the gravity lift, hang right and look for the overshield (it's right next to the big pool of coolant). Now throw a plasma grenade, then immediately after throw a frag, then grab the overshield and jump. If done correctly, both grenades will go off at the same time, and with the added force of your jump, you will be propelled up to the top of the gravity life. Warning: On the higher difficulties, there are a large number of very powerful, very angry enemies up there, and this may not be the best route to take.

As you may or may not know, while an overshield is charging up (right after you first pick it up), you are completely invincible. This exploit can be used to quickly jump up to the gravity lift at the end of the below-the-ship part of the level instead of running all the way back around it. As you approach the area with the gravity lift, hang right and look for the overshield (it's right next to the big pool of coolant). Now throw a plasma grenade, then immediately after throw a frag, then grab the overshield and jump. If done correctly, both grenades will go off at the same time, and with the added force of your jump, you will be propelled up to the top of the gravity life. Warning: On the higher difficulties, there are a large number of very powerful, very angry enemies up there, and this may not be the best route to take.

==The Maw ==

===The Maw ===

'''Skipping the Maw bridge'''

'''Skipping the Maw bridge'''