Sonic Mania made an appearance during a panel at San Diego Comic-Con with Sega giving a first look and description of the Special Stages found in the game.

No one knew if they were going to be new stages, or revamped ones from the Sega Genesis classic Sonic the Hedgehog games. In the presentation the stages were described as being very similar to the SEGA CD and Saturn Sonic games, where they have you chase down a UFO to collect a Chaos Emerald. They also announced that the game will have cutscenes similar to Sonic 3 & Knuckles, and it will have a Sonic CD inspired opening animation everyone will be able to see on August 14.

You can see a still image, showcased on The Sonic Stadium Twitter account. That's actually all they have shown. You can also see the moment in which it was introduced in a video by YouTube user Sollux Captor at the bottom of the post:

Alongside the reveal, we also got a track from the score of the game, created for the Special Stages and titled "Dimension Heists."

In case you're not aware, Sonic Mania, which is being developed by Headcannon and PagodaWest Games in collaboration with Sega and Christian Whitehead, will offer a mix of new levels and updated versions of classic Sonic stages. Sonic the hedgehog, Tails the fox and Knuckles the echidna will all appear in the game.

While Sonic Mania is scheduled to be released in August, there are two new Sonic games releasing this year, and both are trying to bring back the nostalgic gameplay and visual style of the classic Sonic games. If you want to see more footage for the upcoming games, you can view twenty minutes of gameplay for Sonic Mania and Sonic Forces from E3 2017.