Get eaten by the bird.
Reach the stomach of the bird
Reach the stomach city
Reach the stomach city's upper zone
Reach the Acid Ocean
Reach the small intestines
Reach the large intestines
Reach the colon
Reach the Missile Chamber
Obtain the launch ending
Obtain the escape ending
Obtain the launch and escape ending
Discover the Skull of the First
Discover the Skull of the Second
Discover the Skull of the Third
Discover the Skull of the Fourth
Discover the Skull of the Fifth
Discover the Skull of the Sixth
Discover the Skull of the Seventh
Discover the Skull of the Eighth
Discover the Skull of the Ninth
Receive the Blessing of the Nine