System Shock (the first one) - very good graphics for its time and quite innovative - one of the first fps where choosing the right weapon and ammo really did make a difference. Also the way you had to shortcut doors, open locks in a "cyberspace"-world and find the clues(sometimes heads ;-))to progress in the game, was awesome. What was best is something which lacks most of the time with new games: atmosphere! The thrill when Shodan spoke from a screen in your back, you turn and a new creature rises before you..... I do miss that.