I played all the parts of Hitman but the best was Hitman 2, hard to get silent assassin on maximal difficulty, but it is not impossible.
The last 2 Hitmans(Contracts, Bloodmoney) suck they are too easy, and you can finish them in 1-2 days if you know how to hide in the shadows.
Some friends on mine say that the game is junk because you can finish it fast, yes you can if you kill everyone.
