There are two possible ending sequences, good and bad. For the good ending, defeat the final Boss. For the bad ending, lose to the final Boss.
Armored Glide
Once you obtain the Armor Defense power, you will be able to use this trick. It can be used to catch up and attack enemies with force. When you get close to an enemy that you can glide over him, revert to normal Alex then initiate a glide. While gliding, activate your Armor Defense power. This will allow you to maintain your glide as long as you do not release it or dash. This will allow you to glide over stationary enemies and attack with more force. This is especially useful when fighting Elizabeth Greene (the Times Square Boss).
Attack animations
When consuming enemies, use different attack powers such as the Whipfist or the Blade to see different animations. Each attack power has a few animations to show off.
Avoiding death
When your health is low, do not fight with hunters. Climb up to higher building so that hunters cannot reach you, or stand and watch as the military kills all hunters.
Better landings
When jumping, use a dash just before landing. If timed correctly and if the drop was not too great, you should land at near full speed.
Body Surfing
Select the "Extras" option at the main menu. Select "Cheats", then enter Right, Right, Left, Down, Up, Up, Up, Down as a code to unlock Alex Mercer's devastating body surfing ability. A message will appear to confirm correct code entry.
Defeating Elizabeth Greene
Contrary to popular belief this Boss battle is easy. Long before the battle, purchase all upgrades that allow you to do +3 Devastator attacks, upon max health. It is also a good idea to get all the upgrades you can via "Consume". The Boss is massive. Notice that under her life bar are other bars. These are some what the Boss' stabilizers, making her vulnerable only after you have severed them. At the beginning of the battle she will do a scream attack. Be careful. Scale up a building or whatever else you have to do. It is very easy to avoid. You will also have Hunters and Infected chasing you. Use the full body armor and claws/blade. Max out your health by running around and consuming. It is easy and the only issues you might have are Hunters, though with the upgrades one hunter can nearly boost your life to max, allowing for maximum Devastator attacks. This is one of your first Devastator attacks you will learn. Scale a building, boost over to her, fall, and initiate the attack. You will see quickly that the Boss' stabilizers are being damaged. Note: Every round the stabilizers' life will increase, meaning that you have to follow the tactics in the same way, and it will just take slightly longer. Strike her with the Devastator. You should have a chance for more, unless she does multiple attacks (green orbs that track you, spitting concrete and screaming). The armor reduces the amount of damage inflicted, allowing you enough time in between attacks to initiate the Devastator again. Once the stabilizers are done, she will fall and you can attack normally. She will then retreat (leaving you plenty of red life orbs to consume) before shooting out of the ground again, with more stabilizer life and "backup". Ignore the backup. This tactic works nicely, but if you get low on health, run away from her view and keep consuming. After she falls a total of three times you will have defeated her.
Extended change
Hold the D-pad when using the armor power, vision power, shield power, or attack powers to see an extended change in disguise. Each power has their own mini-cinematic. You can test it with or without the armor on.
Extended gliding
Jump into the air and glide. When you start descending, use air dash and press A(2) to fly again. You can repeat this until you run out of air dash (two maximum), for a total combo of three glides and two air dashes). You can glide for three times as long with this trick, allowing you to cover more ground.
Finding Infected water towers
Squawking crows usually circle the Infected water towers, making them easier to find. As soon as you unlock the Infected Vision you can see the water towers that are infected. They will glow the orange color like any other infected.
Gliding
If you have Double Airdash and Glide, by using the Glide, Dash, Glide Dash trick you will be able to reach much farther distances.
Hard difficulty
Successfully complete the game under the Normal difficulty setting.
Helicopter jumping
To do this trick you will need the ability to Jump Kick so that you can fly towards the first helicopter of The Strike team. You can also use the Whipfist's Grab upgrade to latch onto an enemy helicopter. Double Jump can also be useful. To start, jump up and Jump Kick or use the Whipfist Grab to latch onto the first helicopter. Do the button event to kill the pilots. Fly up as high as possible and look for the next target. Make sure to use the Lock On ability. Jump out of the current helicopter and Jump Kick towards the next helicopter. You can keep doing this as long as there are helicopters. If you fall, quickly use the Whipfist Grab. Note: This can be very challenging but if done successfully you can attack numerous helicopters without ever touching the ground.
New Game+ mode
Successfully complete Story mode. You can now replay Story mode with all powers and upgrades previously unlocked. Note: New Game+ is only unlocked for the difficulty setting that you have completed (and any lower difficulty settings).
Platinum events
Earn a "Gold" rank in all events. Note: This may also unlock some Radical events.
Remaining undetected
To remain anonymous and destroy the detectors, hijack a chopper and let your disguise meter cool down. Keep at a distance and make sure that the disguise meter is low. Target the detectors and fire the turrets. This will allow you get to the base without detection.
Starting a New Game+ on a different difficulty
After unlocking the New Game+ option for the Easy or Normal difficulty, it is possible to start a New Game+ on a difficulty that it has not yet been unlocked for. To do this, under New Game+, select Easy+ or Normal+, whichever is applicable. Instead of saving as prompted, press B to back out of the selection. Then, select a difficulty for which the New Game+ has not yet been unlocked. Save the data when prompted to begin the game. You will now begin the game with New Game+ status, without having unlocked it for the corresponding difficulty.
Thermobaric tank
If you want to use or find a Thermobaric tank after the mission where one appears, go to the event "Rolling Thunder". Hop in and cancel the event to use the tank. If you cannot find it or do not know if you have unlocked it yet, pause game play, select "Events", then "Kill" and scroll down until you find "Rolling Thunder".
Various Achievements
Complete the following achievements to unlock Microsoft Gamerscore points.
Achievement
How to unlock
Au (40 points)
Achieve a rating of Gold or better in all Events.
Brain Trust (20 points)
Complete all Consume Events.
Children Of Blacklight (20 points)
You've completed the Supreme Hunter Boss Battle.
Cleanup (10 points)
Kill 15 characters with a single Whipfist attack.
Crossing The T (10 points)
You've completed the Hunter Boss Encounter.
Endless Hunger (10 points)
Consume 200 characters to boost your health.
Errand Boy (10 points)
You've completed the Specialist Boss Fight.
Evolutionary Step (10 points)
Use the Upgrade Menu to acquire an Upgrade.
Gunning (10 points)
Destroy 20 Helicopters in a single Helicopter flight.
Half-Truths (10 points)
Complete a mission without causing a single Military Alert.
Hard To Kill (60 points)
Complete Story Mode in any difficulty without dying.
Hope (20 points)
You've discovered the truth behind Hope, Idaho.
In Plain Sight (10 points)
Evade 10 strike teams.
In The Web (20 points)
Consume 50 Web Targets.
Infiltrator (20 points)
Infiltrate 10 Military Bases disguised as a Commander.
It's Him! (10 points)
Patsy 5 military personnel.
Mankind Is Your Mask (40 points)
Complete 3 missions without causing a single Military Alert.
Misconception (20 points)
Destroy 25 Infected Water Towers before they hatch.
Nice Guy (40 points)
Complete the game while consuming 10 Civilians or fewer.
On Instinct (20 points)
You've completed the Mother Boss Battle.
One Thousand Suns (40 points)
You've completed the Supreme Hybrid Boss Battle.
Origin (20 points)
You've discovered the history of Elizabeth Greene.
Polymath (40 points)
Collect all Hint Collectibles scattered across New York City.
Pt (60 points)
Achieve a Platinum Medal in all Events.
Repossession (10 points)
Seize 50 vehicles from enemy hands.
Return Fire (10 points)
Catch any object tossed by a Hydra; and throw it back.
Revenge Revisited (60 points)
Complete Story Mode on hard difficulty.
SME (20 points)
Gain the ability to drive and fly all vehicles.
Self-Deception (20 points)
Discover what happened to Alex Mercer through the Web of Intrigue.
Speed Bumps (20 points)
Run over 500 characters in a single tank.
Streetwise (50 points)
Collect all Landmark collectibles scattered across New York City.
Surface-To-Air (10 points)
Shoot down 50 helicopters while driving armor.
The Butcher (30 points)
Kill 50 characters in 5 seconds.
The Cleaner (20 points)
Destroy 10 Military Bases or Infected Hives in New York City.
