I'm not as good as I used to be, but then I guess I probably only play as much in a week now as I did per day before, if that.
Oldest game I have installed (and have played in the last year) is Head over Heels - a Spectrum game from 1987 in PC remake form, and it's still a great game work of art.
Entering a room and going "I remember this", then flashing a puzzle because of a 25-30 year old memory, does give a warm fuzzy feeling.
Now I'm thinking of how dumbed-down such a game would be if made today, and it's made me sad. :'(