It needs to do a lot more than that if you want to have something that doesn't alias like crazy. And significantly more if you want it to sound like a game boy.
Well, the output of the wave shaper approach in the article is exactly the same sharp digital square wave that you'd get from a trivial square wave generator.
But I overlooked the point that the GP mentions that the processor source code must be loaded from a separate JS file. That's some quite annoying overhead.
What I was trying to imply was that it's not enough to build a square wave generator to sound like a game boy. Even if that generator in the game boy was a perfect square wave generator, which I'm not sure it is.
The sound created by that generator passes through a fairly complicated filter known as The game boy's speaker. To properly create a game boy sound, you need to find or take an impulse response of that speaker and convolve it with the output of your oscillator.
Well, and a single recorded impulse response is probably not enough, either, if you want to be super accurate. The directivity pattern is probably awful and shaping the sound as well.
I know all of that. But I just didn't want to get into these details in this thread.
But I overlooked the point that the GP mentions that the processor source code must be loaded from a separate JS file. That's some quite annoying overhead.