You can probably assume that. At this point the only mystery is whyMetallic Madness was brought back to production in order to assist in the creation of TM, which you directly proceed to after fighting Egg-GachaAside from those there's enough hints to link the rest together.we go from Stardust Speedway on Little Planet back to Hydrocity on Angel Island, and later from Oil Ocean back to Lava Reef, again on Angel Island.
There's a suspicious lack of transitions in the later half of the game, and some unused assets that I think were meant to be used in them.
It looks like
Eggman somehow tethered Little Planet to Angel Island. In Lava Reef, you can see Little Planet through the holes/craters in the ceiling BG (where you'd see the Death Egg in S3K). There's also a new construction/production city in lava Reef, with a big rocket in the BG that looks the same as the platform you fight Heavy Rider on. So I guess you'd have rode the rocket to Little Planet from there? There's also an unused cliff edge you can debug to after that fight. Knuckles actually has a transition in this level, in that he rides the old Sky Sanctuary teleported.
Transition wise, I guess it's;
Angel Island -> Green Hill
Phantom Ruby Warp
Green Hill -> Chemical Plant
Phantom Ruby Warp
Chemical Plant -> Studiopolis
Zoom Pipe
Studiopolis -> Flying Battery
They jump onto it ala S3K
Flying Battery -> Press Garden
This one, I guess Flying Battery docks at Eggmans press factory?
Press Garden -> Stardust Speedway
Phantom Ruby Warp. Eggman wants Metal Sonic back, and I guess starts his plans to use Little Planet again.
Stardust Speedway -> Hydrocity
Fuck if I know. If we assume Eggman has tethered Little Planet to Angel Island, then somehow Sonic and Co get knocked off the planet?
Hydrocity -> Mirage Saloon
I guess we have to assume Mirage Saloon is located in a desert on Angel Island? A transition here would be nice, but this is also seems like a little time skip, as Sonic and Co group back up and recover the Tornado.
Mirage Saloon --> Oil Ocean
Sonic and Co use the Gun gimmick to shoot over there. I guess this Oil Ocean isn't the same one from Sonic 2, but a new one Eggman has created on Angel Island to fuel his growth on Little Planet.
Oil Ocean -> Lava Reef
Easier to explain, Sonic and Co somehow end up underground from Oil Ocean, back into Lava Reef.
Lava Reef -> Metallic Madness
Sonic and Tails use a rocket from Lava Reef, Knuckles uses a Hidden Palace teleporter. They end up back on Little Planet.
Metallic Madess -> Titanic Monarch
Sonic and Co. travel to the giant Eggrobo being built on Little Planet. Enter it, travel up it and face the final battle.
Transition wise, I guess it's;
Angel Island -> Green Hill
Phantom Ruby Warp
Green Hill -> Chemical Plant
Phantom Ruby Warp
Chemical Plant -> Studiopolis
Zoom Pipe
Studiopolis -> Flying Battery
They jump onto it ala S3K
Flying Battery -> Press Garden
This one, I guess Flying Battery docks at Eggmans press factory?
Press Garden -> Stardust Speedway
Phantom Ruby Warp. Eggman wants Metal Sonic back, and I guess starts his plans to use Little Planet again.
Stardust Speedway -> Hydrocity
Fuck if I know. If we assume Eggman has tethered Little Planet to Angel Island, then somehow Sonic and Co get knocked off the planet?
Hydrocity -> Mirage Saloon
I guess we have to assume Mirage Saloon is located in a desert on Angel Island? A transition here would be nice, but this is also seems like a little time skip, as Sonic and Co group back up and recover the Tornado.
Mirage Saloon --> Oil Ocean
Sonic and Co use the Gun gimmick to shoot over there. I guess this Oil Ocean isn't the same one from Sonic 2, but a new one Eggman has created on Angel Island to fuel his growth on Little Planet.
Oil Ocean -> Lava Reef
Easier to explain, Sonic and Co somehow end up underground from Oil Ocean, back into Lava Reef.
Lava Reef -> Metallic Madness
Sonic and Tails use a rocket from Lava Reef, Knuckles uses a Hidden Palace teleporter. They end up back on Little Planet.
Metallic Madess -> Titanic Monarch
Sonic and Co. travel to the giant Eggrobo being built on Little Planet. Enter it, travel up it and face the final battle.