More:Halo 2: Missions: Containment

From GameWinners

Contents 1 Face in the sky 2 Sniping location 3 Run very fast

Face in the sky

With a sniper, get to an area where you can see the Halo in the sky. On each side of it, there is a face, but you can see it when you zoom in.

Sniping location

Look near either base from the gate switch. Turn to your right, look up, and you will see a large outcropping. Get in a Banshee and fly to the top of the outcropping.

Note: This will be easier if you have a second person on top of the closeable gate watching, so you can have a third person view. To get to this location, there are certain conditions. You must be at the Red base (or at least be able to remain there if you are Blue). You must also have a Spectre, a sniper or beam rifle, a rocket launcher, and at least three of each grenade. When you are at Red base (the one without light blue blotches all over its walls), get in the Spectre at its starting point. Turn around. You will see a small ramp that leads to another ramp and to the top floor. On the left side of that ramp is a rock wall. Line the Spectre up with the bottom right corner of the slope and the top left corner. Move your view all the way up as far as it can go. Then, go straight while boosting right into the wall. Never stop boosting. If done correctly you will cling to the wall. Go up a short distance then turn left. This is where you will need a second person watching. At the bottom on the ground are three rocks (a short stubby one, a long one, and another short stubby one). The Spectre should go slightly bit past the third rock (if counting from right to left). You should be adjacent with another rock wall. Then, go up. If you follow parallel to that other wall while going up, when you reach near the top there will be an "invisible hole" in the "invisible wall", just big enough for the Spectre. From there, you can snipe people and blow up tanks and Banshees that may discover you. This is where the grenades are used. Make sure you keep one rocket with you, in case this fails. When you run out of ammunition, you must kill yourself if you cannot reach the hole again. Use the grenades first. If they do not work, use a rocket. If you are in split-screen mode, turn on team changing in game variants so that you can just change teams to kill yourself without losing a point. If on Xbox Live and you fail to kill yourself, you will be stuck -- nobody really looks up there and you will not get killed.
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Run very fast

Use the following trick to can run very fast for a short period of time. First, find a fusion core and one of the brown metallic ramps in the center of the map. Run into (but do not hit) the fusion core. Continue running into it to keep it moving. Run the core up one of the center brown ramps, run it across it, then back down. When you run back down with the ramp (with the fusion core still in front of you) you will run over the top of the core. This will propel you very fast in the direction you were running.