Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "hitmancontracts.ini" file in the game folder. Add the following lines to the end of the file.
EnableCheats 1
EnableConsole 1
Then, press ~ during game play to display the console window. Enter one of the following codes at the console window to activate the corresponding cheat function.

Effect - Code
God mode - god 1
Invisibility - invisible 1
All weapons and items - giveall
Level skip - end level
Unlimited ammunition - infammo