Well, he says "custom engine" in the article but, he used XNA. When people hear "built an engine" they tend to assume the person spent years building it from-sc

Well, he says "custom engine" in the article but, he used XNA. When people hear "built an engine" they tend to assume the person spent years building it from-scratch. XNA is hardly from-scratch. I think, in this case, the author meant he didn't use one of the big commercial engines. Aside from all that, I also agree that it's not a really big mistake.