Extra Datura bullet:
Hold A and tap B to get one Datura bullet while the Shadow Man or any other strong opponent is attacking. This will only occur when your character is out of Datura bullets and the opponent is on the screen.
Item select:
Toggle between the Satlink screen and the Datapod Info location until items that are needed (bullets, datura root, etc) appear on the map.
Hidden message:
Insert the game disc into an audio CD player and play track 2 to hear an audio message from Sewer Shark.
