"Mystic Cave Zone (Simon Wai Prototype) - Sonic the Hedgehog 2" is a high quality rip of the Simon Wai prototype version of "Mystic Cave Zone" from Sonic the Hedgehog 2.
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At 0:02, the melody changes to the World 2 final level theme from The Fancy Pants Adventures, a Flash game whose second world was released in 2008.
At 0:38, the track loops.