1991 Developer Team Office...
	Completion bonuses...
	The 50 Floor Dungeon...

When you get to the Underworld for the first time, defeat Golbez in the crystal room. Get access to the armory, then go down to the weapon/armor room. Go behind the pillar that is between the two shop desks. Move up from there to enter the hidden Lali Ho Pub. Then, move to the right to the dark spot on the floor. You can move through the wall from here. Climb down the stairs to reach the hidden 1991 Developer Team Office entrance. Enter the hidden area to talk to the game developers.

Complete the game and continue from your cleared saved game file, then explore the surface of the moon until you see a face-shaped rock. Enter it to access a fifty level dungeon. The Music Player option will also be unlocked in the Extra menu.

Defeat the game once and then go searching on the moon's surface for a boulder that's shaped like a head, with a face.