Best Hitman game made!
I love the Hitman series and personally I think this game is a classic. The graphics are a little dated by now, but the game play is still solid and original and there is tons of fun to be had. I bought this game twice, once for PC and love it so much I got it again on 360 to get the achievements. This is one of the few games I played through multiple times. You can buy and upgrade weapons, but most importantly you can beat every level multiple different ways. The best way of course is to never fire a single gun, and make every death look like an accident if you can and never get discovered. This will take some experimentation, but when it all works out it is really satisfying to pull off.