A while ago, I started sniffing around the internet for a bunch of early-90s games that I enjoyed growing up. There's this lovely thing called Abandonware. If there's an old game that never gets re-released on another platform, or bundled with other software, or otherwise recycled, it just fades into the ether. It's been abandoned, and as such, becomes free on the internets.
So I collected a few classic DOS titles and played them for a bit. Alex latched onto them, and I taught him to play them.
Fortunately, I was always attracted to Sim titles, and things that were stealth-educational.
There's Sim Tower:
And Sim Ant (which I didn't actually play, but my siblings enjoyed, so I'm learning it alongside Alex)
Sim City 2000, which I utterly adored and played for hours and hours:
The Oregon Trail original version. I have died of dysentery/snakebite/broken legs/etc. etc. etc. But I reached Oregon. Alex hasn't yet managed to do this because the text menus stymie him.
And finally there's Rollercoaster Tycoon, which I actually had on disk and didn't need to download. Much, much love has gone into this game.