Game Cheats:
Easy money, all weapons upgrades and gadgets at the start:
When you start the game, you will have to complete the prologue mission. Then,
you will proceed to your plane to start the main missions. You can also start
side missions by talking to your team. Talk to Grim to get four side missions
to complete before you start the main missions. When you complete all of Grims
missions, new gear will be unlocked under the "Customize Gear" option. You
will now have all the stealth gear and can start Mission 1: Safe House. This
is one of the quickest missions in the game, and if you complete it without
killing anybody and stay undetected, you will get a lot of money when you
complete the mission. Once you finish the mission, you will be back at the plane. While on the plane, go to the "SMI Panel". Display the map, and view the missions. You will have the option to replay the "Safe House" mission. Replaying and completing this mission eight times will get you more than enough money to buy all the planes upgrades and all of Sam Fisher's gear and weapons.
Easy "Hostile Shield Secured" achievement:
At the end of "Special Missions HQ", you will encounter an enemy with a
shield. A short cutscene will begin playing when you enter the room.
Eliminate the other enemies, and let the Infantryman get close to you. Then,
shoot his shield until he breaks down. You will then have a couple of seconds
to get behind him and eliminate him with hand-to-hand combat.
Pick up his shield to get the "Hostile Shield Secured" achievement.
Easy "4th Echelon Commendation":
Use the following tactics in the indicated missions to complete the game on the
Perfectionist difficulty while staying undetected and not using lethal force and
get the "4th Echelon Commendation", "4th Echelon Officer", "No Kill Option Engaged", and "Tactical Style: Ghost" achievements.
Easy "Evidence Concealed" achievement:
When you kill the first enemies in Mission 1: Safe House, you will be in an alley. There are a total of six enemies and five containers in this area. One container is in the alley, and four are in the building you need to enter. Eliminate all of the enemies, and then put one in each of the five blue containers to get the "Evidence Concealed" achievement.