[scottostler]

I don't disagree, but when I watched for about 15 seconds he was inserting printlns, trying to debug something related to sprite collisions. So I'd guess he still does some of that.

But the better answer is probably that he's been making games for two decades, according to wikipedia. Presumably he's long since worked through much of what you or I would need to think about when putting together a 2d tile game.