The first episode aired as a preview on June 15, 2012, with the official premiere on June 29.
It’s out there somewhere in the woods, waiting.” Gravity Falls is an American animated television series, created by Alex Hirsch (writer for Cartoon Network's The Marvelous Misadventures of Flapjack and Disney Channel's Fish Hooks).
Every episode has a unique, non-repeating "secret message" at the end of its credit scene.
The key for decoding the secret message is always incorporated in the opening theme-song scene.
This is a Caesar cipher, which, in this case, uses a letter three places back from the letter it represents (e.g., A=X, Z=W, etc.) and is used from episode 101 ("Tourist Trapped") to episode 106 ("Dipper vs. Starting with episode 107 ("Double Dipper"), the cryptogram must be solved using the Atbash substitution cypher, which reverses the alphabet (meaning that A=Z, B=Y, and so on). After the song ends, a creature similar to the Eye of Providence is flashed.