Just curious what the oldest game is that you've played, and whether you enjoyed it or not. I'm less interested in the technical experience, so you can use the original release date, even if you played a more modern implementation.
For me, Fate/stay night just barely beats Clannad, by a few months. Both were released in 2004, and both show their age a little bit (Clannad in its convoluted branching, Fate in its resolution options), but are perfectly playable. But of course both are super popular classics, so I wonder if you all had similar experiences with more obscure or older titles.
I've always liked this, it has pretty much everything you could want in a personal project: a catchy name and a whimsical idea that is just on the edge of being actually practical.