Before you type any cheats, you must enable your console. Enabling the game console is quiet easy: 
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- Open My Computer. Browse to C Drive>Program Files>eidos>Iointeractive>Hitman. This is the default path where your Hitman Folder is located. Search for the Hitman.ini file and open it with notepad or any other text editing software.
- Type this line at the bottom of the hitman.ini file: enableconsole 1
- Save the file, close it and start the game (note: make sure you have a backup copy before editing any game files)
Adding Hitman PC game Cheats in the Game Console:
After editing the Hitman game file, it is time to invoke the console and type cheats. During any level of the game, hit the (~) Tilde button. This will open the game console. Enter the following cheats (all without quotes):
For acquiring all items (including weapons with maximum ammo and all other items): Type “giveall”
For becoming invisible: Type “invisible 1” to turn on and “invisible 0” to turn off invisibility.
God Mode: Type “god 1” to turn on god mode and “god 0” to turn it off
For accessing infinite ammunition: Type “infammo”
Eliminate the targeted enemy: type “ip_debug" and then press the shift key and F12 simultaneously (shift+F12) once it has been enabled.