[mbeattie]

He didn't talk about the last level for some reason.

[noffle]

The astute reader will also note that Five and Six were also not discussed. From the fourth paragraph, "I will be discussing a subset of the nine challenges".

[alttag]

Also skips 5 & 6. In a closing paragraph the author mentions the discussed levels were "some of my favourite levels".

[mcpherrinm]

Perhaps that's the "would-be" part. The portion of people who solved it dropped off fairly heavily for the last level.