I also started out on the Apple ][, writing my own versions of the games I saw in the arcades (donkey kong, pacman, joust, etc).
My kids are old enough to be curious about how games are actually built, and we've had fun building an adventure game in basic, and a version of asteroids in C. We had planned to build something this summer, so this book of yours is an ideal next step which we can work through. I think they'll really get a kick out of seeing how it all goes together. (okay, okay, I admit it. Nostalgia hit me hard and I just want an excuse to fire up my old Apple ][ again.) Regardless, I just hit "order" on Amazon.
Add VT100/ANSI terminal emulation and you can run Wordstar, Rogue, dBase 2 etc.
If you're subtracting the CPU emulator what is the point of doing any of this?
On more modern systems, the CPU is only a tiny bit of the equation. You might have to emulate the graphics pipeline, the audio processor, the input mechanism, etc... This makes the process of writing an emulator more tenuous, as those are not nearly as straightforward to implement, and might be badly documented.
If you look at the really modern platforms (like the Switch or 3DS), CPU emulation is barely 20% of the work.