He hasn't gotten to gameplay because it is meant to be an educational series, which means skipping the parts that don't serve the educational purpose.

I've followed Casey's approach but taken a different path. Instead of focusing on covering anything an engine could do, I started making my own game.

And I discovered that once you get the basics of a platform layer and some GPU communication down, it's pretty easy to start throwing together a real game.

I'm doing it. I've got a real game with real gameplay, actual levels, real things you can do. All of this after a year or learning.