Winding Tunnel

Twisting Tunnels, also referred as tunnels, are tight, fast-paced passageways and one of the many gameplay elements in the Sonic the Hedgehog series games. They are usually placed inside the structure or the underground sections of a zone. When a playable character enters a Twisting Tunnel, he/she curls into a ball mode and rolls down the Twisting Tunnel, while gaining momentum speed at the same time. Most of the time, they somewhat serve as automated sections in the game.

Despriction
Twisting tunnels are placed inside of the structures in the zones, with the shape of the twisting tunnels being different in each game. While some of the twisting tunnels can be very linear, they are usually shaped as winding routes, coming in shapes such as "Ƨ" formations. After the player enters the twisting tunnel, he/she has less control over the playable character, though the playable character automatically gains more speed after exiting the twisting tunnel. While not usually being able to, if the player is able to gain enough running momentum, he/she is able to backtrack through twisting tunnels as well. If the player does not have enough running speed when attempting this, the playable character normally rolls back out of the aperture.

The twisting tunnels first appeared in Green Hill Zone in the original 16-bit version of Sonic the Hedgehog. In this game, the twisting tunnels usually go through tall level structures in "Ƨ" formations. This later returned in Sonic the Hedgehog 2, where similar "Ƨ" shaped tunnel routes appear in Hill Top Zone and below the shuttle loops. Casino Night Zone featured different, automated tunnels that are set in-between the sections of the Pinball Shooter and the shuttle loop/pinball arena. Hidden Palace Zone in both prototypes and 2013-released versions feature similarly functioning pipes.

Sonic the Hedgehog CD contains many Rounds, where twisting tunnels are featured. They are extremely useful to gain enough of speed for the time travel. In Palmtree Panic, they are featured along with several ones, that can even converted into shuttle loop at the underground in the present, good and bad future versions of the Zone. When the player usually spins out tunnels, hatches close the aperture. Linear tunnel pathways are featured on Collision Chaos. "Ƨ" formed tunnels are also featured at Quartz Quadrant, while several linear tunnels contain conveyor belt systems to transport the player either up or down. Many tunnel sections are also featured at Wacky Workbench and Stardust Speedway.

Angel Island Zone Act 2 in Sonic the Hedgehog 3 features long and winding tunnel sections, that are blocked by breakable pile of rocks. Hydrocity Zone Act 1 features limited amount of linear tunnel parts most of the time below shuttle loops. IceCap Zone Act 2 contains tunnel sections, which are similar to ones from Hill Top Zone. At Flying Battery Zone in Sonic & Knuckles, when the player enters the linear tunnel part from below, the player normally doesn't turn into curling mode, but gets bounced by Springs inside the tunnel to reach to the end of it.

At Neo South Island Zone Act 2 in Sonic the Hedgehog Pocket Adventure, only two tunnel sections are seen, while more linear tunnel sections are featured at Cosmic Casino Zone. 3D variation of Green Hill in Sonic Adventure 2 features tunnel sections, which are heavily automated. In Sonic Advance, "Ƨ" formated tunnels are featured at Angel Island Zone. In Sonic Advance 2, some regular twisting tunnels are featured at Hot Crater and Ice Paradise, while Music Plant featured ones that loosely looked like French horns. In Sonic the Hedgehog 4: Episode I, "Ƨ" shaped tunnel routes oddly contain Dash Panels inside to give extra amount of speed. Tunnel sections are also seen in Green Hill of Sonic Generations.