It is listed in the level select menu in the Simon Wai prototype but selecting it simply brings the player to a empty level. Chemical Plant Zone music plays, and the player will simply fall to their death at the bottom of the stage. Enabling debug reveals that the only objects in this level are the two default objects, a ring and a teleport monitor.
Tom Payne, the zone artist in charge of this level, stated that it was dropped before it was even started. Instead, he worked on the third act of Metropolis. In the Sonic Jam strategy guide Yuji Naka stated basically that the third act of Metropolis Zone used the layout meant for Genocide City and that it was meant to be a single act. Here is the quote in full:
|“||Act 3 (of Metropolis Zone) was going to be a different Zone that would only appear once (one act)... We had already finished the map, and it would have been a shame to waste it, so this is what we went with.||„|