Originally Posted by MartinKhan
"Let's give something exclusive to the PC version, screw all the other platforms in which we released the game!"
Hold on a sec, think about it. Valve wants this DLC to be free, regardless of platform. If what was said about Microsoft is true, then there are obviously going to be no new achievements for the Xbox. But why should that mean that the other platforms don't get any?
Anyway, that probably wasn't even why there weren't any new achievements. If I remember correctly, none of the other co-op courses had their own specific achievements. To be honest, the only thing in the DLC that I think is achievement-worthy is beating the course.