We had a C64 when I was little, but not much in the way of games for it.
This one was the best out of the ones we had. I still know the background music by heart.
The most memorable PC games from when I was a kid:
Dinosaur Safari. I was crazy obsessed with Dinosaurs when I was a kid, and I lived and breathed this game. A photography game that pre-dated Pokémon snap, and still one of only 3 games I'm aware of in the genre. Edutainment.
FinFin.
(Fansite). This thing could barely even be called a game, because your actual ability to interact with anything was almost nil. You could offer food (which would usually be ignored) and talk into the microphone at the titular flying dolphin creature (which as far as I ever could tell only really registered volume). Apart from that, though, it was a beautifully illustrated real-time view into an alien world, with its own flora and fauna and weather. It had actual seasons and things that followed the real calendar, ala Animal Crossing, with plants growing and wilting and different natural phenomena occuring at different times throughout the real-life year. For example, the nuts on the trees in the forest glowing at night in the fall, or the "double lunar eclipse" that would happen one night a year when the two moons lined up.
There was a ton of weird wildlife that would show up, some of it very rarely, so I basically turned the game into a wildlife photography sim using the screenshot function. Staying up late at night watching an empty forest or stream in the hopes of catching a glimpse of a rare nocturnal creature. Seeing a pattern here?
Anyway, the game apparently got a lot of very harsh reviews from people who thought watching the sun set in real time over an alien rainforest is boring and stupid. Whatever.
Also, a demo for Exile II: Crystal Souls was one of the first really awesome RPG-type games I ever played and will hold a special place in my heart forever. It just recently occurred to me that I'm a responsible adult with their own purchasing power now, so I was finally able to buy the whole Exile series on CD from Spiderweb.
Edit:
Forgot another big one.
Oddballz. The best (strangest) virtual pet program ever made. From PF Magic of the excellent Petz series before Ubisoft acquired it and turned it to shit.