Here are some games I used to play with my son a lot when he was a kid. The first two were on CD-ROMs that came with our first computer.

Lemmings (1991)
Lemmings are critters that, if you don't stop them, will mindlessly walk off the edge of a cliff (and disappear bloodlessly). Your object is to stop them, corral them, and direct them toward a safe place, saving as many as possible within a limited time.
Click for Wikipedia article
Click for a website where you can download the program(s).

Sam & Max Hit the Road (1993)
LucasArts, which developed this program, doesn't have it for sale any more, so it seems there ought to be a web site somewhere where you can download it for free, but I can't find it. I'm a bit outside my area of expertise here, so maybe somebody else can help.

SimCity
First there was SimCity, which came to be called SimCity Classic. We started with a later version, SimCity 2000, and graduated to SimCity 3000, and now I understand there are later versions which I haven't tried. Though the newest version has always been kinda pricey, I believe you can get older versions very cheap. I'd say SimCity is best for older kids, 12 & up, but I think there is a version for younger kids called SimTown.
Here's the Wikipedia article about the earliest version, and you can follow links from there to later versions.