One of the best PC games I played was System Shock 2...very scary and atmospheric. Has new mods out now but they aren't working with my computer.
Of the classics I would have to say Bruce Lee on the old 48k Spectrum! Run around collecting lamps and avoiding the green yamo and ninja. The green yamo could be controlled by a second player...deadly!!
Also Goldeneye on the N64! Now there's a gem...great multiplayer as well. I jury-rigged this four-way split screen cardboard thing that we salo-taped to the TV to block off the other 3 views from each person...worked brilliantly! 2 people sat on the floor and 2 on chairs behind them. Prevented evil 'screen watchers' <img src="/ubbthreads/images/graemlins/evilgrin1.gif" alt="" />