Here are some compiled cheats for Prototype researched across the web:
Cheat Mode
At the main menu, select the "Extras" option, then choose the "Cheats" selection. Enter one of the following codes to activate the corresponding cheat function. If you entered the code correctly, a message will appear.
Body Surf ability
Enter Right(2), Left, Down, Up(3), Down as a code to unlock the Body Surf ability.
New Game+ mode
Successfully complete Story mode. You can now replay Story mode with all powers and upgrades previously unlocked. Note: New Game+ mode is only unlocked for the difficulty that you have completed (and any lower difficulty).
Platinum events
Get a "Gold" rank in all events to unlock the Platinum events. Note: This may also unlock some Radical events.
Hard mode
Successfully complete the game on the Normal difficulty to unlock the Hard difficulty.
Easy experience
An easy way to get experience points is to get a helicopter, preferably without alarm. Go to any Infected area, and search for water towers containing Hunters. These are easily found by going to the area where the crowds are circling. This indicates where an Infected water tower is located. Lock on to it, and blow it up with a rocket. It should only take one rocket with a direct hit. You will get 8,000 experience points per water tower. With 200 rockets in an attack helicopter, you can get 1,600,000 total experience points. Then using the machine gun, you can destroy forty more water towers. You can then use the remaining homing missiles to blow up a hive for more points. Get another helicopter, and repeat the process. The water towers will respawn after a short period of time.
Note: This trick requires the ability to hijack helicopters and have Infected Vision, obtained later in the game. Hijack a helicopter, then activate Infected Vision. Look for the bright orange water towers scattered throughout the city, primarily in the Infected areas. Shoot them with the helicopter's weapons. For each water tower destroyed, you will get 10,000 experience points, which are important this far in the game. Note: Water towers respawn continuously for unlimited experience points.
Finding Infected water towers
Squawking crows usually circle the Infected water towers, making them easier to find.
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.
Helicopter jumping
This trick requires the ability to hijack helicopters and Jump Kick so that you can fly towards the helicopter. 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 pilot. 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.
Defeating the Time Square Boss
This Boss battle may seem hard, but it can actually be easy. Long before the battle, purchase all upgrades that allow you to do +3 Devastator attacks, upon max health. It is also recommended you get all upgrades possible through the "Consume" option. The Boss is massive. Notice that under her health bar are other bars. These are 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 can. 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, but with the upgrades one hunter can nearly boost your health to max, allowing for maximum Devastator attacks. This is one of the first Devastator attacks you learn. Scale a building, boost over to her, fall, and initiate the attack. You will quickly see the Boss' stabilizers are being damaged.
Note: Every round the stabilizers' health 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 destroyed, she will fall, and you can attack normally. She will then retreat (leaving you plenty of red health orbs to consume) before shooting out of the ground again, with more stabilizer health 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.
Defeating the final Boss
Quickly switch to Armor and Blade after the cutscene ends. Having Infected Vision will help. Stay away from the Boss until he starts to jump. After he lands, attack him with an Air Blade Slash. He will become stunned after a few good hits. Grab him and repeatedly punch. If you are taken down to critical level, use a Devastator move to stun him.
Experience points for Orbs
The experience points awarded for each Orb picked up is based on how many Orbs have already been collected.
Hint Orbs
1: 5,000 each
10: 7,500 each (and 10,000 bonus)
15: 12,500 each (and 25,000 bonus)
35: 15,000 each (and 50,000 bonus)
Landmark Orbs
1: 2,600 each
10: 5,000 each (and 10,000 bonus)
25: 9,750 each (and 25,000 bonus)
100: 15,000 each (and 50,000 bonus)
125: 17, 250 each (and 60,000 bonus)
150: 20,000 each (and 70,000 bonus)
Easy "Half-Truths" achievement
Play the mission where you lead the Leader Hunter to Ragland. Successfully complete your objectives without being noticed. You will be instructed to lure the Hunter. Look at the map. It is mainly infected zones with two blue military zones at the far east and west. Notice the unclaimed area directly up the middle. Keep in this area to avoid alerting the military and get the "Half-Truths" achievement.
Easy "Misconception" achievement
After you get your powers back (when Ragland helps you), it will be easy to find infected water towers. Lock on to one, then go to the corresponding building. Get on the roof, and use the flying kick attack to do a lot of damage. Then, quickly follow up with a combo to destroy it. Note: The "claws" powers will make this easier.
Easy "Speed Bumps" and "The Butcher" achievements
After you have the ability to hijack a tank, drive one into a red zone. You should find a lot of fleeing civilians (normal and infected). Drive on the sidewalk to run them down and get "The Butcher" achievement. You can also unlock the "Speed Bumps" achievement after running over 500 people in a single tank.
Easy "The Cleaner" achievement
You can destroy ten Hives easily because the military softens them up by the time you get there. Get a tank and destroy them to get "The Cleaner" achievement.
Achievements
Accomplish the indicated achievement to get the corresponding number of Gamerscore points:
Revenge Revisited (60 points): Complete Story Mode on hard difficulty.
Endless Hunger (10 points): Consume 200 characters to boost your health.
Trail Of Corpses (30 points): Kill 53,596 infected.
Wrecking Yard (20 points): Destroy 2,000 vehicles.
Misconception (20 points): Destroy 25 Infected Water Towers before they hatch.
Brain Trust (20 points): Complete all Consume Events.
Streetwise (50 points): Collect all Landmark collectibles scattered across New York City.
Polymath (40 points): Collect all Hint Collectibles scattered across New York City.
Half-Truths (10 points): Complete a mission without causing a single Military Alert.
Mankind Is Your Mask (40 points): Complete 3 missions without causing a single Military Alert.
The Butcher (30 points): Kill 50 characters in 5 seconds.
Return Fire (10 points): Catch any object tossed by a Hydra; and throw it back.
Gunning (10 points): Destroy 20 Helicopters in a single Helicopter flight.
Cleanup (10 points): Kill 15 characters with a single Whipfist attack.
The First Thread (10 points): Unlock the Web of Intrigue.
Self-Deception (20 points): Discover what happened to Alex Mercer through the Web of Intrigue.
Web Of Knowledge (60 points): Acquire all nodes of the Web of Intrigue.
It's Him! (10 points): Patsy 5 military personnel.
In Plain Sight (10 points): Evade 10 strike teams.
Infiltrator (20 points): Infiltrate 10 Military Bases disguised as a Commander.
Threat Elevated (20 points): Destroy 25 strike teams.
Repossession (10 points): Seize 50 vehicles from enemy hands.
SME (20 points): Gain the ability to drive and fly all vehicles.
Surface-To-Air (10 points): Shoot down 50 helicopters while driving armor.
Evolutionary Step (10 points): Use the Upgrade Menu to acquire an Upgrade.
Unnatural Selection (40 points): Acquire all available upgrades.
The Cleaner (20 points): Destroy 10 Military Bases or Infected Hives in New York City.
In The Web (20 points): Consume 50 Web Targets.
Au (40 points): Achieve a rating of Gold or better in all Events.
Nice Guy (40 points): Complete the game while consuming 10 Civilians or fewer.
Hard To Kill (60 points): Complete Story Mode in any difficulty without dying.
Speed Bumps (20 points): Run over 500 characters in a single tank.
Pt (60 points): Achieve a Platinum Medal in all Events.
Additionally, there are seven secret achievements:
Crossing The T (10 points): You've completed the Hunter Boss Encounter.
Errand Boy (10 points): You've completed the Specialist Boss Fight.
Children Of Blacklight (20 points): You've completed the Supreme Hunter Boss Battle.
On Instinct (20 points): You've completed the Mother Boss Battle.
One Thousand Suns (40 points): You've completed the Supreme Hybrid Boss Battle.
Hope (20 points): You've discovered the truth behind Hope, Idaho.
Origin (20 points): You've discovered the history of Elizabeth Greene.