A "Sneak Peek" is when a path lets a player travel though another area of a game without allowing entrance into the meat of the area.

In the map below, A goes to B through E. The player doesn't fully reach E until making it through C and D.

Foreshadowing

Sneak Peeks can be used to build mystery and foreshadow things to come. In Super Mario World, going through the pipe in Donut Plains takes Mario to a cliff overlooking Koopa's Castle, but Mario cannot reach it from the cliff.

Connections of Discovery

Sneak Peeks are also a great way to connect two areas in interesting ways. Having too many connections between areas can lead to too much of an open world feeling. Keeping the connections to a reasonable amount can help with sense of discovery. Sneak Peeks are a tool that can be used to keep the discovery without adding connections to the main portion of the area.

In The Legend of Zelda: Ocarina of Time, Taking two lefts in the Lost Woods will bring you to an area with a bridge that cannot be reached. It is the same bridge that is crossed when entering or leaving Kokiri Forest!

Behind the Scenes

Sneeks Peeks can give the player a Behind The Scenes view of an area that they wouldn't normally get to see. They can serve as the theme park train that goes underneath the roller coaster.