Nearly all enclosed structures involve doors for entry, exit, and partitioning of rooms. Many doors are designed as realistic obstructions or background art, and might not be utilized by the player or the game engine. Doors can be used to transition slowly into next room that is loading into memory from a disc medium. This is notably the case in some versions of Resident Evil, Metroid, and Castlevania games.
A shutter-style door is a certain type of obstruction that may appear suddenly, to force the player to complete a certain task before opening again, or as a concealed entrance to be discovered and unlocked. Shutters are normally built in to the surrounding wall. To operate they can lift or slide if they are a single piece of material, operate as a rolling wheel, or open like an iris.
A gate is normally an exterior obstruction attached to a fence, and may have protection against climbing over the top of it.