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.