Before You start keep in mind You'll be changing file so make a copy before You start. Now, for this one You'll have to edit hitman.ini file in your Hitman game directory and add line 'enableconsole 1'. When playing the game press [~] or ['] to enter console mode and type:
infammo - Unlimited ammo
giveall - All weapons with max ammo
invisible 1 - Invisibility
god 1 - God Mode
Press TAB to cycle through all commands.
Max Payne style mode (slow-mo)
Just press the scroll lock button during the game and the game slows down, however, just like the bullet time mode in Max Payne, the mouse pointer moves at a near normal rate, allowing you to accurately take out (head shot) numerous guards in a matter of seconds, and then press the scroll lock button again to remove the slow-mo style.
Multiple Gun Combo Trick
This trick will let you have up to 15 rounds in any gun.
1. Make sure that you have a Beretta 92 in your inventory.
2. Select the gun you want to have 15 rounds in, and make sure that is the ONLY thing you are holding.
3. Drop the gun on the floor.
4. Take out your Beretta 92 and pick up the gun you just dropped.
5. You will be holding both guns at the same time, and you will have 15 rounds in both guns since they always shoot together.
When you have completed all the mission objectives, don't exit yet. Instead, press F1 for the mission status screen to appear. When the "success" message appears press ESC to go back to the game. Then repeat the process. Each time you will be paid the reward for the mission.
Rate of Fire
When in the last level "Meet your brother" you will gain access to a minigun, in repetition mode there is a serious delay between the click and the first shot, because the gun has to get running before it can shoot. Change into single-shot-mode instead, the first shot will be much faster, and the rate of fire will still be extremely high!