One of the most rewarding and contrasting cinematic detours for audiences is the chamber piece, sometimes referred to as a chamber drama or chamber film. This diversified genre is discernible by its use of a small cast of characters, often meshed over a short period of time, and in a limited environment, often times just a single location.
Also, though not always, chamber films are based off of plays and/or have their derivation due to a modest or micro budget. Because of these impediments, which can also be very creatively vitalizing, the resulting films are often subversive, risky, and incredibly innovative.
Shane Scott-Travis, Taste of Cinema