As per the mail sent to DirectHex
Last Ninja 2 : Lost in New York
This was it for me on the Commodore 64. I played through it so many times (It was a multiload on tape also !) and enjoyed it everytime. Graphically it was superb for the 64, in its day I would say it was about the best ever.
Thief 2
Well this is a classic in its own right. Fantastic visuals and sound. The first one was spoilt by the zombies on it on some of the levels. But this one was amazing, so well put together, nothing beats when you managed to sneak up behind a guard, nick his arrows and purse then knock him out and hide him. Can't wait for Thief 3.
Secret Of Monkey Island
The first Monkey Island game in the series. I played this one through on the Amiga and still play it on the emulator to this day. The humour was amazing and the interface with all the keywords on the bottom worked really well.
Metal Gear Solid
Personally this has to be the PS1's finest hour. Brought a whole new meaning to the stealth / action genre and in a league of its own. (Still not a patch on Thief 2 really though but enyoyable nontheless) Very involved story with really long cutscenes that were a bit annoying at times except the one in the snow where you finally kill Sniper Wolf.
Giants : Citizen Kabuto
The humour in this game really done alot for me. Also the end of the first level where he plants the Union Jack flag. It was 3 separate stories and very different play modes for each of the characters. So well put together and the graphics were fantastic, It ran in 1024x768 on my 533 Celeron and Voodoo 3 card at the time.
Have to add a number 6 to this also !
Mafia
This game didn't get the recognition it deserves at all. A whole city was built up from scratch for it with traffic and people everywhere you went. Story on it was very involved and pieced together perfectly with the main character telling parts of the story and you acting them out, you got a real feeling for the characters in this game and the end is so moving. This game was and is a masterpiece and the PS2 owners out there will soon be able to play it.