In the 80s, my sister and I spent many, many hours playing video games on our dad's PC (this was well before Windows, remember). Ever since we left the house, and the cats peed all over the boxes of old 5.5-inch floppies in my parent's basement, we have been looking for versions of these games to play again. Luckily for me, one of them has its own domain: Digger. There's no Mac version, though there is a Java-playable version without sound. Nice. I know, we wasted our youths, but I can't go back in time and fix it now.
There's one game we have both been looking for. We can't remember the name of it. It was a sort of educational game. Your character was represented by a hat and feet (yep, that Fountains of Wayne song sometimes makes me think of it wistfully), and your job was to stop the spread of a virus, which was also represented by little figures (I can't remember, but I think the virus turned the town residents into zombies, sort of - the graphics were primitive). All travel - by you and the virus - was done by train. I think the educational element had to do with map reading, as you and the virus travelled to cities all over the United States. Sometimes you'd get to a town and see many regular little people milling around, and sometimes you'd arrive at a town and everyone was already infected. The virus was extremely hard to contain and winning was a challenge. Also, the near-silence - the only sound effects were the chuffing of the train arriving and departing the various station - made everything that much creepier. Anyway, if anyone reads this and has any advice for my quest, please email me.
EDIT: My sister remembered a few other details: Once the townspeople get infected they look furry or spiky. Also, and most importantly, the virus was transferred from person to person by them just bouncing off of each other; when they'd touch, there would be a "shing!" noise indicating viral transmission - like the sound old video games would use when a sword would be drawn, or during the opening screen of the Nintendo game "Blades of Steel." (Also, she doesn't remember the guy being just a hat and feet, but she doesn't remember what he looks like, so I'm letting that stand.)