The Pillar of Autumn (Halo: Reach)
Make you way to the Mongoose. Some people do a cool slide jump, but they're pretty difficult. You can try Backflip's, Dark’s, or Auraxade’s. Make sure you grab one of the Rocket Launchers on the inside of the building, so that it will be full. Go for a drive, and don’t get out of your Mongoose until you're at the Bugger cutscene. Run through the Buggers, and run through the boneyard. When you reach the Shade Turrets, head for the door with Grunts walking out of it. Find the grunt with a Fuel Rod Gun and borrow it from him. Keep running through the level until you reach the Hunters. Run for the door that opens when the Hunters are dead. Crouch a couple feet away from the window that is closest to that door, then jump through the window. It’s a bit tricky, but if you practice it a few times, you'll get it. After you make it through the window, touch the other side of the door to trigger the loadzone to load the enemies. Keep running through the level until you reach the dry dock. Head for the huddle of Jackals and Grunts, and take them out with Nades and Fuel Rods. Make sure that all of them are dead. If some are still alive, kill them after the first wave of enemies. Just rocket each group of Brutes and Grunts that drops out of the first Dropship. For the second wave (“hold them off until Keyes gets here”), situate yourself in a spot where you can see where both groups of enemies will land. When the first group jumps out (a Brute Chieftain with a Fuel Rod Gun and some Grunts), shoot two rockets at them and immediately reload. You'll have just enough time to reload before the other group of enemies jumps out. Shoot one rocket at the group (it should kill all of them, but Fuel Rod any stragglers), then turn back to where the first group was. There should be another Brute Chieftain with a Gravity Hammer heading toward you. Rocket/Fuel Rod him to death, then sprint for the Dropship that drops enemies on the elevated structure. Try to make it there before the enemies drop with a reloaded Rocket Launcher. Due to a glitch similar to the one on Long Night of Solace, if you kill the Brute Chieftain right when he lands, the game will think that all the enemies are dead and Keyes will leave for the landing pad. This only works if every previous enemy is dead. If you don’t kill him fast enough or didn't kill all the enemies, just kill everyone else and go trigger the cutscene. After the cutscene, simply run to the MAC gun and trigger the timer to end the level. The trigger is the last flight of stairs to the MAC gun. Regardless of how many enemies are dead, the game will start a timer that’s something like 1:20 long. When you hear dramatic music and “fire now, Lieutenant, hit her in the gut,” do as you're told!