Modify Starting Cash
You can edit the dark.cfg file and add the line "cash_bonus n" N represents the amount of cash added to the beginning of a mission.
Skip to Next Mission
Press [CTRL] + [ALT] + [SHIFT] + [END] to skip to the next mission.
Increase Cash (Bug Exploitation)
Just before completing the mission, do a save or quicksave. Complete the mission and save it in a different save slot. Reload your last save or quicksave before completing the mission. Complete the mission again. The statistics screen should now have ADDED TOGETHER the loot from BOTH mission completions. Apparently, the variable which stores treasure amount at the end of the mission is not being cleared between loads. You can keep doing this until you have all the cash you need to buy out the store at the loadout screen for the mission immediately following.
Various Cheats
Add to dark.cfg:
Cheats_Active
LockCheat
Lockcheat makes sure almost all locked doors and chests will be openable without need of keys and lockpicks.
Anti-cheats:
Add to user.cfg:
FailOnSee
FailOnKO
FailOnKill
No Killing Rule
This involves editing the USER.cfg file, first make a copy of the file, then add the following lines "cheats_active", "nokillgoalcheat" this will alow you to win with out worrying about the no killing rule in some missions.
Landing softly
Press [Crouch] before landing onto a surface and the sound produced will be softer.
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.
Attach through walls
You can swing your sword through walls when an opponent is on the other side.
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.