Thief 2: The Metal Age

Level skip:
Press [Ctrl] + [Alt] + [Shift] + [End] during game play.

More money:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "user.cfg" file in the game directory. Change the value after the "cash_bonus" entry to increase the amount of additional money available at the start of each level.
pctech32.

Easy no kill missions:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "dark.cfg" file in the game directory. Enter "cheats_active" on a new line, then enter "nokillgoalcheat" on the next line. You will now be able to pass the objectives in any mission that requires you not to kill anyone.

Almost all doors and chest unlocked:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "dark.cfg" file in the game directory. Enter "cheats_active" on a new line, then enter "lockcheat" on the next line.

Expert mode:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "dark.cfg" file in the game directory. Enter "cheats_active" on a new line, the enter one or more the following lines after it.

FailOnSee
FailOnKO
FailOnKill

Each mission will be easier to fail.

Level select:
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "user.cfg" file in the game directory. Scroll down to find the lines:

;Running Interference
;starting_mission 1

;Shipping ... and Receiving
;starting_mission 2

There are two lines for each mission. To start at the desired mission, delete the semicolon before the second line, for example ";starting_mission #". When a new game is started, you will begin at the selected mission.
suchy fried.

Better night vision:
If you are having trouble seeing in the darkness, use the following trick. Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "cam.cfg" file in the game directory. Change the "Gamma" level from "0.5" to "0.3". Note: Do not use the "-" or "=" keys or the gamma settings in the option menu, as this will cause the game to return to the default gamma range.
cj1a.

Hint: "Blackmail" mission:
Once inside the main gate to the estate and facing the front entrance, you can get in easily by going slightly to the left of the entrance after taking out the two torches on the door. The bushes conceal an entrance to the basement. Watch out for the patrol guard.
Ahmed Hamza.

Glitch: "Unwelcome Guest" mission: Unlimited arrows:
In the "Unwelcome Guest" mission (the one played in the demo version), get to the part where you see four guards arguing with each other. They will start to fight (two on one side and two on the other). If the guards from the tower die, climb that tower and hide behind one of the wooden pillars (the ones closest to the guards are recommended). The guards will naturally see you before you reach the pillar, but you will have time to hide before being hit by their arrows. While you are hiding, make them see you from time to time so they shoot arrows at you. If done correctly, the arrows will get stuck in the pillar, and you can lean and catch them without being harmed. Do this until you have as many arrows as desired.
João Godinho.

Hint: Landing softly:
Press [Crouch] before landing onto a surface and the sound produced will be softer.
Ahmed Hamza.

Hint: Fun with objects:
When playing any level where hammers can be found, use [Action] to pick it up and carry it around. When you are behind or in front of a guard or peasant, throw it at them. They will instantly be knocked out or killed if hit in the correct spot. This can be useful if you are backed into a corner or are out of arrows.
JakeTheJeweler88.

Hint: Avoid falling damage:
Press [Esc] while falling from a high location before hitting the ground. Although your character may grunt, he will not take any damage.
robert_jones.

Glitch: Attach through walls:
You can swing your sword through walls when an opponent is on the other side.
jnmw_2000.

Glitch: More money:
Save the game immediately before completing a mission. Complete the mission as usual, and save the game in a different save position. Reload save that was made before the mission was completed. Complete the mission again. The statistics screen will combine the money from both missions. Repeat this to earn as much as needed.