Name of game to test whether you can spot layout/formatting issues

Something like six months to a year ago there was a post showing a web based game where you were challenged to spot subtle layout/formatting issues from a list of examples displayed. They would start fairly easy (obvious font differences) and get increasingly hard to spot (tiny differences in line settings etc)

Can anyone remember what it's called.

I've tried googling, but naturally game/test/QA/layout/formatting in various combinations all throw up loads of more common sites about design in general that seem to drown out any chance of me finding the original. Thought I'd bookmarked it but again struggling to find it given my memory failing me on the exact name or the best terms for it.