Genocide City Zone is one of the 4 levels that was scrapped in Sonic the Hedgehog 2.
A hacker known as "Sonic Hachelle-Bee" created the hack "Sonic 2 Long Version" to change this. Reviving Genocide City was one of the reasons for this hack's creation.
Genocide City is actually a single-act zone. In this "Long Version" hack, the entire level layout in Act 1 is repeated in Act 2. The only exception is at the end, where Act 1 has the regular end signpost, but Act 2 has a boss.
The boss is just a harder version of Chemical Plant's boss. It's harder because there's less ground for Sonic to stand on as Eggman attacks you by dropping rotten sewer water on you.
The almost entire lack of this level in the final version of Sonic 2 is how Metropolis Zone got an Act 3. At the time, several of Sonic 2's development staff were from the Japanese Sonic Team division.
They were looking for a "cool" English-sounding word to use for this zone. So they went with "Genocide". Unfortunately, this was before they knew what that word meant: Killing an entire group of people based on either their race, nationality, religion, etc.
It was actually going to be called "Cyber City" at one point.
All confirmed by Yuji Naka, one of the 3 original creators of Sonic the Hedgehog. If you DO try to get to this in the final version, however, you'll only be greeted by an glitchy void. You would have to use the game's Debug Mode to travel, as you'll die in a matter of seconds after you appear.
The zone originally used Chemical Plant as its song, but the "Long Version" hack gives replaces it with Casino Night's 2 Player theme. It's still probably evident since this zone has Chemical Plant's Badniks and boss.
Wood Zone:
http://www.youtube.com/watch?v=-1cUkByL7u8
Dust Hill Zone:
http://www.youtube.com/watch?v=A3QBbBkfFvs
Hidden Palace Zone:
http://www.youtube.com/watch?v=Sfhgwkl5_3A
Rock: I don't know what that covers.
Winter: That can be for the blue section of Dust Hill. That's where everything looks cold.
Cyber Night/City: Those are supposed to be alternate names for Genocide City. I've heard of Cyber City more than Cyber Night, though.
The rest of the zone were discovered well, though, and were probably hacked to be completely playable, too.
Carls493 1 month ago