KPA soldiers strategy:
When attacking while in Cloak mode, you automatically lose all your energy. Instead, go to Armor mode (not Strength mode as this takes up energy when you attack), immediately shoot a soldier in the head, then go back to Cloak mode. They will not see you and you will still have all your energy (and even may gain 1 to 3 %). While you are transitioning to Armor mode, you will have a couple seconds where you are still invisible to the enemy, which allows you to adjust if you are sniping. Even if you reach your time limit that you are invisible after turning off Cloak mode, you can still shoot around and might get away with not being seen as they occasionally panic and move around too much to notice you. You can use this to stay in a stationary location that the A.I. does not touch and easily take out a huge group, (such as the area directly below a watch tower).
Alien Troopers strategy:
To kill Alien Troopers without shooting, when the Alien Troopers jump in the air and levitate shortly doing nothing, they are about to charge at you and possibly kill you in one hit. When they do this, get out of the way. When they charge and miss, there will be an instant where they are idle. Run up to them, grab, and throw them. This may be slightly harder at certain angles. The moment you throw them, they will die (under the Easy difficulty setting at least).
Hidden weapons on "Recovery" level:
In level 2 "Recovery", under the Delta difficulty setting there is a rocket launcher at the roadblock where there is a truck full of KPA. There is also a rocket launcher and a Precision rifle leaning close to the back wall outside of the house at the radar station. There are at least two rocket launchers at a small white building adjacent to the town hall (KPA HQ). There is a rocket launcher at the gas station cash register. Along with the rocket launchers in the school, those two tanks are easy to destroy. There is also enough Precision rifle ammo at the second floor pillbox of the KPA HQ to max out your capacity.
A Little Trouble Parking - Discover the fate of the Lusca's Call.
Easy Darlin' - Rescue the hostage.
You Knew, Didn't You? - Regroup with Prophet upriver.
Very Strange Readings - Infiltrate the excavation site.
Livin' Up To Your Name - Board the VTOL for extraction.
Pro-Aircraft - Destroy all AA guns around the harbor.
Enjoy The Fireworks - Destroy the cruiser.
Empty Platform - Secure the train station.
You're On Your Own - Proceed to the mining complex.
One Careful Owner - Reach the end of 'Onslaught' in the tank you started with.
Going Underground - Enter the mines.
It's On Like General Kyong - Defeat General Kyong.
I'm Coming Home - Escape the mysterious structure under the mountain.
Expedition Team - Escort Prophet to safety.
I'm A Marine, Son! - Help the marines evacuate.
Strickland Would Be Proud - Defeat the flight deck invader.
Close Encounter - Secure victory in the Battle of Lingshan.
Following Orders - Complete 3 Secondary Objectives.
Tank Buster - Destroy 5 enemy tanks.
This Is My Rifle - Customize a weapon to use all 5 modification points.
Special Forces - Kill 200 enemies.
Long Distance Relationship - Kill an enemy 200m away.
Something For Every Occasion - Use all weapon attachments.
Nano Ninja - Perform 5 consecutive kills without being spotted by an enemy.
Knock-off Knockout - Kill an enemy Nanosuit soldier with a Strength punch.
Zoology - Pick up an animal.
Catch This! - Kill 10 enemies by throwing an object at them.
Delta: Act I - Complete 'Contact', 'Recovery' and 'Relic' on Delta difficulty.
Delta: Act II - Complete 'Assault', 'Onslaught' and 'Awakening' on Delta difficulty.
Delta: Act III - Complete 'Core', 'Paradise Lost', 'Exodus' and 'Reckoning' on Delta difficulty.
Without Question - Complete 6 Secondary Objectives.
No Fly Zone - Destroy 5 helicopters.
Team Raptor - Kill 400 enemies.
Weapons Master - Perform a kill with every firearm.
Choke Hold - Kill 20 enemies with grab.
Marathon Man - Speed sprint 3km.
Keen Observer - Tag 30 enemies using the binoculars.
Crysis Controlled - Complete the game on any difficulty.
Cool In A Crysis - Complete the game on Hard or Delta difficulty.
Perfect, Soldier! - Complete all Secondary Objectives.
Platinum Trophy - Earn all Bronze, Silver, and Gold trophies.