I like "the Codex of Alchemical Engineering" and other games made by Zachtronics. It's the kind of games fun enough that you can sit a child in front of them and they won't feel like they're being tricked into doing their homeworks instead of playing.
Unfortunately his early games were written for Flash, so I doubt anyone here has ever played them. There's a project for the preservation of Flash game. It's mostly open source (games binaries aren't open source) https://bluemaxima.org/flashpoint/ . They have other Zachtronics programming games in their archive.
Coincidentally, the guy who stole poor indie dev Zach of well deserved fame and money by cloning his most audacious project, Infiniminer, into Minecraft planned a programming game with programming the emulated 16-bit processor (DCPU-16) as part of the gameplay: https://en.wikipedia.org/wiki/0x10c . It will never be released, Notch just gave up.
I wrote only a single piece of Redcode for Core War in my life, but I've lost it. Could be challenge #2? It was an amusing idea but a terrible fighter.
>>7
I knew this one, but I've never played it. I didn't know it was still actively developed. I thought it was some Java thing from the past.
https://en.wikipedia.org/wiki/Programming_game
Never heard of the old ones, like "System 15000" and "Hacker", but they don't really sound like programming games. More like pentesting games.