Unlock the "Vidmaster Challenge: 7 on 7", "Vidmaster Challenge: Brainpan", "Vidmaster Challenge: Annual", and "Vidmaster Challenge: Lightswitch" achievements in Halo 3. Unlock the "Vidmaster Challenge: Classic", "Vidmaster Challenge: Deja Vu", and "Vidmaster Challenge: Endure" achievements in Halo 3: ODST. Then, go to Bungie.net to get a download code to unlock the Recon armor in Halo 3: ODST. Note: You will need a valid and linked Bungie.net account to get the download code.
Successfully complete the indicated task to unlock the corresponding mission in Firefight mode:
Successfully complete the indicated task to unlock the corresponding character in Firefight mode:
During the ending credits, press Right Analog-stick Left. Do this until the camera pans over to the left of the screen to see Buck playing with one of the weird monkeys from Halo 3.
Successfully complete the game, and do not interrupt the credits. The Epilogue video will begin playing after the credits end.
Enter Forge mode on the Multiplayer disc. Load one of the following maps, and use flying camera mode to reach the Skull location. Once you find a Skull, position yourself above it, toggle out of flying camera mode, and hold the button you have mapped for picking up weapons (default is RB). Your character should fall past the skull and pick it up on the way down. If you miss it, simply try again.
Citadel
Heretic
Longshore
If you have completed the game and are having trouble finding the remaining Audio Logs, when searching for Audio Logs, electronic devices such as pay phones, ticket booths, cars, cross walks, and anything tied to the Superintendent or city will go off basically announcing there is an Audio Log around waiting to be collected. Always be on the look out for the yellow glow in VISR mode on one of these things to find the Audio Logs. -From: Daniel Walker
The units you can get Audio Logs from in the Mombasa Streets all have a picture of the Superintendent on them (the green smiley with white eyes and no mouth).
The 30th (last) Audio Log for Sadie's Story is in Mission 8: Date Hive. However, it is in a locked area until you find the other 29 Audio Logs in the Mombasa Streets. Once you collect the 29 Audio Logs, play Mission 8: Date Hive until you reach the hole to get to Sub-Station 9. Instead of the Superintendent closing off the hole so your teammate cannot get through (and ultimately get killed by Drones), he will climb down the hole with you. Continue playing until your teammate says something similar to "Wait here, I need to go check something." Follow him, and he will reveal his true purpose for coming here and will fight you. During or after the fight, you can scan the phone on the wall next to the dead body to find the 30th Audio Log. Note: Finding the Audio Log will slightly alter the scene, specifically the part where Dare and the Rookie find Vergil. Instead of Dare telling the Rookie not to shoot, the Rookie will tell Dare not to fire and instead whistle for Vergil to come out.
While in VISR mode, look for secret doors. Accessible doors will turn the amber outlines of objects in front of them blue. This is easiest to see on your weapon. Watch for them because many of these doors hide data terminals.
To quickly defeat an Engineer, use the Covenant pistol. Fully charge it to kill Engineers with one shot. This works in both Campaign and Firefight mode.
In the "Prepare To Drop" tutorial mission, when the Carrier jumps to Slipspace Rupture, look closely at the right of the Carrier. You will see the Amber Clad of Commander Keyes getting into the Slipspace Rupture along with the Carrier. In Halo 2, during the end of the "Metropolis" mission cutscene, you will see the Amber Clad of Commander Miranda Keyes to the right of the Carrier entering the Slipspace Rupture along with the Carrier. This is definitely a reference to Halo 2 for a couple of reasons. Halo 3: ODST takes place in New Mombasa, and the Carrier is floating next to the space elevator. In Halo 2 you are also in New Mombasa, and at the beginning of the level on the bridge, you can see the space elevator and the Carrier floating next to it. In both Halo 3: ODST and Halo 2, when the Carrier jumps there is a big EMP wave.
Spartans are "half human, half machine" as noted by Bungie. Orbital Drop Shock Troopers (ODSTs) are basically ordinary Marines, only they are highly trained, but they are not like Spartans. Bungie made a mistake by making the player slightly like Spartans for a few reasons. In the game, you are as tall as a Spartan when you are standing next to an ODST squad mate. You can wield a Gravity Hammer, which the only ones known to actually wield them are Spartans and Brutes, not ODSTs. You can melee Brutes to death, while only Spartans can do that. The melee attacks performed by people with lower ranks than Spartans do not affect Brutes at all.
Successfully complete the indicated task to unlock the corresponding Avatar Award:
Before boarding the Scorpion, give your rocket launcher to any Marine riding in the tank. Note: You can also pick up the other rocket launcher from behind the tank and hand it off as well. Any kill the Marine makes counts toward the achievement. The Marine has infinite ammunition, which makes getting the "Both Tubes" achievement much easier.
Get a Plasma pistol. Use an overcharged shot to destroy a Brute's shields, then use the silenced pistol to get a headshot. This works for Jackals as well; use the overcharged shot to disable their hand held shield, and then shoot them in the head to help you get the achievement. -From: Graeme Todd
Play Mission 3: Uplift Reserve, and get the Warthog at the beginning, then load it up with Marines. Shots fired from the Marines do not count against the achievement, but you cannot use the e-brake or horn. Just try to go through the level as quick as possible.
Play Mission 3: Uplift Reserve, and hijack a Ghost (recommended because of the boost ability) or Brute Chopper right away. Get past the Wraiths, and continue to the next area. Run over as many Covenant as possible, and go to the next area with all the Shade Turrets. There is a Shade Turret all the way to the left. If you have the Ghost, you can drive behind it on the cliff wall. Boost into the turrets; it should only take down your stamina. Recharge your stamina, and continue this process to destroy all the turrets and Covenant. Proceed further into the mission. At a current point you should hear the colonel talk about the "asset" that they must retrieve. The next part may require a few attempts. Drive around all the enemies and Wraiths, and enter the tunnel. Continue the rest of the mission by outrunning the enemies. Note: Remember to stay in cover.
There is a slightly faster and bit easier way to get the "Vidmaster Challenge: Classic" achievement on Mission 3: Uplift Reserve. When you get around the first corner from the starting point, there is a small battle going on between a Wraith and a few smaller Covenant vehicles firing on a squad of UNSC forces. Hijack a Ghost from that area, and boost all the way to the end of the level. The boost on the Ghost does not count as firing a shot. If your Ghost is getting destroyed, there is a new one on the other end of the bridge you cross as the Space Elevator collapses. Also, you can climb the hill just after this location using the boost feature, instead of going along the path and getting shot at by the two Shade emplacements. Note: E-braking and honking the horn with the Warthog counts against you.
Play on the Legendary difficulty with the Iron Skull enabled. Two Mongooses which you can use as transport will appear inside the first open tunnel you can walk into after starting on the highway. Also accompanying the Mongooses are four rocket launchers with 999 shots. Take each part of the highway slowly, and make sure to cover Dare when she gets overwhelmed.
Accomplish the indicated achievement to get the corresponding number of Gamerscore points: