Dust Hill Zone
This zone only appeared in Sonic 2 Alpha and Sonic 2 Beta version A, but the name stayed in Sonic 2 Beta version B for Mystic Cave Zone. Acts 1 and 2 are finished, but act 3 wasn't. Act 3 is at night and Act 2 is at sunset. There are two kinds of badnicks here: The Buzzers from Emerald Hill and a crocodile-like robot. (looks and acts like the crocodile robot from Rusty Ruin in Sonic 3D Blast) The music is almost the same as Emerald Hill but is different at parts. There is rumor that this zone also appeared in Sonic CD, since there is a missing zone between Palmtree Panic and Collision Chaos and the map of the Little Planet shows a desert area with cacti. The map is shown below. Look to the right. This may be true since Sonic CD and Sonic 2 were being made at the same time, but Dust Hill Zone would have been called Dusty Desert Zone or Desert Dodge Zone if it were to be in Sonic CD.
Could Oil Ocean be the future of Dust Hill? The ground in Oil Ocean Zone is similar to the ground in Dust Hill and oil can come from desert areas. Below is a picture of the ground comparison. I don't know, it looks alike to me. Oil Ocean also fits the Sonic CD pattern of zone names. For example, Palmtree Panic Zone, Quartz Quadrant Zone, and Stardust Speedway Zone. The double letter thing.
The cacti on the Little Planet also have a Bad Future and a Good Future. Look at the picture below. The bad future is to the left and the good future is to the right. There is grass and a building in the good future. Now look at the bad future. The cacti are gone and there is a building there instead. Notice that the building is pouring what looks like oil into the ocean. The ocean is also black like oil. Could Oil Ocean be a bad future of this desert.
In the Sonic arcade game, SegaSonic the Hedgehog Arcade, there was a desert zone with sand and cacti. The name of the desert zone was Desert Dodge Zone. This was the first Sonic arcade game to come out. It came out around the same time as Sonic 2 also. Maybe this is where Dust Hill went. In this game there are 3 characters to chose from: Sonic the Hedgehog, Mighty the Armadillo, and Ray the FlyingSquirrel. The game is like Sonic 3D Blast with grafics and like Knuckles' Chaotix with the rings that link the characters. Below is a screenshot of Desert Zone. The game is unfinished and is To Be Continued after Desert Zone.
Dust Hill is the biggest mystery to me. Below is the original picture of Dust Hill Zone. Sonic, the life picture, and the lettrs all look like they're from Sonic 1. This must have been in Sonic 2 Alpha, since Sonic looks so much like the original Sonic sprite. The only reason I can think of why Sonic is not in the center, is that he was falling really fast from part of the level above him. It's interesting how Sonic 2, Sonic CD, and SegaSonic Arcade all came out around the same time and all are connected to Dust Hill. The more and more I investigate Dust Hill, the more and more it looks like it was actually in Sonic 1. If you've played Sonic Jam and seen the commercial for Sonic 1, it shows Sonic running through a desert with cacti.