Sonic Mania Plus: Mania Mode Part 6: Stardust Speedway Zone (Super Sonic & Tails)
Previously, at the end of Press Garden Zone, I managed to make a glitch happen where the camera doesn't scroll with the following cutscene of Sonic & Tails getting warped to Stardust Speedway Zone. This didn't affect anything going into here, at least.
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For the most part, Plus didn't change anything about Stardust Speedway, until you get to the boss fight against Metal Sonic that is!
The whole fight has gone through a near-complete overhaul. The first section where you're racing Metal Sonic to his robot generator is the same, but the fight against that very generator is easier and less annoying now.
The 8-bit Mecha Sonic still do the most damage to the generator if you knock them into it while they're in ball form, but if you just destroy them on your own, they'll shoot out energy balls that do less damage to the generator. Either way, you have more chances to the blow the thing up.
After you do, the second racing section is MUCH shorter so that you'll reach the end of it faster, and it has a Star Post. That first new detail is great if you're in your Super form at the moment, and the second detail is REALLY helpful for the last new thing out of this fight.
In the finale of this Metal Sonic battle. Instead of having run with Metal Sonic to outrun a giant spiked wall from nowhere, Eggman now throws the Phantom Ruby to Metal Sonic, using it to transform into a new version of his Metal Sonic Kai form from Knuckles Chaotix! He then chases after you like the Great Eggman Robo final boss of Sonic 3 & Knuckles' Death Egg Zone!
Similarly to that, you have to bust open the glass that Metal Sonic contains the Phantom Ruby in. Do that enough times, and Metal Sonic both changes back to normal and falls to scrap. You'd think you'd be able to get that ruby now, but NOPE! An enemy knocks it away from you, and you can't even hit him for it!
Stardust Speedway originally didn't have an outro, but Plus fixes that, too. Sonic and/or his friends quickly find Eggman in a room, but then, after getting that Phantom Ruby back from one of his robots, Eggman quickly warps the heroes to Hydrocity Zone, possibly hoping they'll drown this time, I bet...