Game Secrets:Sonic the Hedgehog 2 (16-bit)

From Sonic Retro

Lost Sprites

Artwork	Name	Description
	ARZ Barrier	Unused door barriers from Aquatic Ruin Zone.
	Unused Balkiry Frame	Unused frame of the Balkiry badnik with landing gear.
	Walking Turtle	Walking sprites of the turtles that pop out of the badniks in Sky Chase Zone. Normally you'll never see this, since the animal never has the opportunity to hit the ground.
	HPZ Icon	Level Select icon for Hidden Palace Zone, which never made it into the final game. The art however, is present in Sonic 3's level select.
	WFZ Laser	Large laser shooting through a spinning platform in Wing Fortress Zone. Never seen in-game.
	MCZ Ring Platform	Weird platform made of rings, placeable using debug mode. It moves back and forth depending on which side you stand on.
	WFZ Spinning Pole	Weird spinning pole that acts like a badnik - you can destroy it, and it can hurt you, but it doesn't actually move.
	Static TV Monitor	Powerup monitor which harms you when broken. Never seen in-game.

Unused Music Track

In the sound test, song $10 is actually a unused song. This has been established to be the music meant for Hidden Palace Zone.

True Level Order

The level order that is used during gameplay is actually quite different from the intended order according to the level slots. A simple level select Pro Action Replay code (FFFE10:??00) can be used to verify this:

Order in gameplay	Actual
Emerald Hill Zone	Emerald Hill Zone (00)
Chemical Plant Zone	Metropolis Zone (04/05)
Aquatic Ruin Zone	Wing Fortress Zone (06)
Casino Night Zone	Hill Top Zone (07)
Hill Top Zone	Oil Ocean Zone (0A)
Mystic Cave Zone	Mystic Cave Zone (0B)
Oil Ocean Zone	Casino Night Zone (0C)
Metropolis Zone	Chemical Plant Zone (0D)
Sky Chase Zone	Death Egg Zone (0E)
Wing Fortress Zone	Aquatic Ruin Zone (0F)
Death Egg Zone	Sky Chase Zone (10)

Level slots 01,02,03,05,09 all lead to Emerald Hill Zone and 08 is actually Hidden Palace. In the Simon Wai prototype some of these were used for scrapped levels. 02 was used for Wood Zone and 0E was used for Genocide City Zone.

Commentary found in the Sonic Jam strategy guide reveals that the level order could have been even more different. It states that Chemical Plant Zone was meant to be the 10th zone back when the game was planned as an 18 zone game.

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Sonic the Hedgehog 2 (16-bit)

Sonic 2