How can I get the
'Guardin' Gnome' achievement in Left 4 Dead 2?
The text of the achievement is the following:
Rescue Gnome Chompski from the Carnival.
So I suppose it has to be done in the
Dark Carnival campaign, but how?
There is an eHow article detailing how to unlock the achievement.
Basically, you need to score 750 on a shooting game in stage 2 of the Dark Carnival. Upon winning, you get Gnome Chompski. You have to carry him into the escape vehicle (at the end of the campaign). You can drop the gnome as much as you want, but you must carry him to the end.
One little tip:
When you are in the safe room at the end of each map, you need to be holding the Gnome for the map to really finish. Closing the door is not sufficient. Might not be obvious for some (like me :))