I Love You When You Rough-House!

The tidy architectural office could use some Proton-based humbling. When trying to find what Stay Puft is looking for before he does, you'll make your way through a pristine architectural office where you will fight a large group of Puft's marshmallow minions; destroy it! Blast everything in the room to bits, and the achievement should unlock as you exit the room with Ray to continue on.