WMG / The Descent

The film takes place in Minecraft
  • And the crawlers are creepers.

Sarah is in a coma after the car crash, and all the characters, including people she knows, are representations of parts of her psyche, and the events of descending into the cave is her mind's representation of slowly descending into death, the death of the characters representing the death of those parts of her brain (NOTE: Applicable only to this film, ignoring the sequel).
http://tvtropes.org/pmwiki/pmwiki.php/WMG/TheDescent