My experience almost exactly mirrors yours. When I was in grade school, there was a shared computer in the hallway outside the eighth-grade classroom, and if the teachers trusted you enough, you could stay in and use it instead of going outside for recess. A few buddies and I would congregate around the PC and play Gorillas. And once we figured out how to edit the source code and do weird things with gravity, or cause tremendous banana explosions, we were hooked! (And, I think several of us went on to become programmers.) It was kind of like the thrill you'd get when you used Game Genie on an NES game for the first time.
I think that's the best way to get kids into coding, not some forcefed programming gui, but "Hey, here's a game you can play in class!" and then just give suggestive nods towards the source code and "what happens if you change this?" Next thing you know, kids are all trying to one up each other's programming, pulling apart the source and putting it back together without realizing that they're programming. I got into electronics by pulling apart toys and looking what makes them tick, there's no reason the same couldn't be done for code.
Yes, thank you, I almost forgot about how it really began with tweaking the code for the game itself! Great memories. Reminds me of how so many old games had .dat files (or something similar) that you could mess with initial settings or screw with the sounds.
This gives me a good idea for teaching my kids to program. Why start from scratch? I'm going to give them a game like this, with code, and see if they can do something crazy with it!
P.S. For me, I became the computer lab teacher's assistant in order to skip recesses or other activities in middle school. Fixed printers, made .bat file menus, good times.
I recall a friend doing something similar with mobs for Quake 1. The game used its own dialect of C, iirc. And it was possible to decompile the relevant files. So after some time he started modifying mods.
That Quake 2 and later required Visual-C++ and such kinda took the spark out of the creative mods, as the entry price became too high.
For instance Quake 1 had a "flight sim" of sorts that was basically done by one guy using Quake-C and some simple, freeware, modeling tools.
There was an attempt at making a successor for it in Quake 2, but even with a larger team etc it basically ran out of steam thanks to the complexities involved etc.
