Going by the following rules:
1) The game was considered good when it came first
2) Graphics are not accounted for
Then Sonic Adventure (the first one for DC) comes to mind. I still have it and remember how good it seemed back then; except for Big the Cat, that was crap even back in the day.
I've tried to replay it recently, and found that the mechanics just don't hold up, to the point its nearly unplayable.
Another good example is The Longest Journey -along with the entire point and click adventure genre I guess. Whilst I didn not play it in its time, I heard so many great things about it. Got it recently through GOG and found the snail pace and tons of exposition unbearable. I can see how I would have liked it back in the day, but today, it just doesn't work for me.