My list, my rules-

Lets start with the obvious. To appear in this list a movie must first and foremost have its narrative screen-time, but not necessarily its characters, restricted to a single and frequently closed location. The locations in question cannot be anything as big a town or open terrain, but must be something much more close quarters. The location is more often than not a room or a building of some kind, but setting a film within these environments does not automatically qualify you for this list. Locations such as the the sprawling Hill House Mansion of Clue or the vast mall of Dawn of the Dead have been omitted. They allow for too much free wheeling movement from the characters to evoke the same sense of stage craft essential to this list.

The power of limited location is essential for inclusion on this list. That said, screen-time outside the location is tolerable, but only if brief, infrequent, and above all relevant to the scenario that confines the narrative to the location. Setting the scene, contextualizing a location, testing the limits of the location, and/or giving a sense of closure are all tolerable and indeed sometimes necessary. Scenes bookending the bulk of the narrative are the most common and tolerable, but spending too much time outside of the location would disqualify a movie (sorry 127 Hours). Flashbacks and dream or fantasy sequences are only permitted under these same circumstances.

Incarceration films such as Kiss Of The Spider Woman, Scum, Hunger, Midnight Express, The Big Doll House, et al, have also been omitted. All of these films are distinct enough to exist as a sub-genre unto themselves. Although they have many of the same narrative features as those films included here, they generally explore one or both of two themes not covered by the films in this list - the (un)just nature of institutional incarceration and/or jail break. The characters from this list do not exist within their location because society deemed it just that they do so. They are in the situation they are in because of a bizarre twist of fate, a supernatural event, or at the mercy of a malevolent force.

The most common type of movie narratives to accommodate these restrictions are ones that focus on the immediate consequences of leaving the location (being eaten by zombies, drowning, getting murdered by a creepy dude, etc) and/or a sense of entrapment and claustrophobia over becoming isolated from the outside world. There are some examples on this list that do not use personnel peril as the dramatic element of the location, but instead focus use common human relations and extended conversations. This is a vastly different tact, but the end result is no less valid to the sense of stage-craft and location focused narrative.

This is by no means a definitive list, I'm pretty sure I've missed a few I'm aware of and undoubtably even more I'm not. Also, quality has not been a deciding factor on whether or not a film is included here. Feel free to make suggestions for films to be added and to make comments about the list or its content.