Cheats:
Tower Of Nanar Co-Op mode:
Collect five golden skulls to unlock Tower Of Nanar Co-Op mode.
Alternate character's color:
Collect four golden skulls to unlock the ability to change the
character's color.
Commander video:
Collect six golden skulls to unlock the Commander video.
Pokemon reference:
Successfully complete World 1, and watch the video sequence. Aban will
talk about the temple of Poko-mum and refer to it as "Pocket Monster",
which is the Japanese title for the Pokemon series of games.